Castlevania has a long history of naming characters with western names that aren't common in the place the games are actually set. I wanted to take a look at all of them and compile them here for your consideration.

Simon Belmont - シモン・ベルモンド (Shimon Berumondo)

Simon's first name IS a name used in Romania. Biblical origin. The katakana character for "shi" is also used for "si".

"Belmont" is a mistranslation of Belmondo here, which is an Italian name. I've heard Simon's last name is after French actor Jean-Paul Belmondo, whose father was Italian. Both Italians and Romanians are known or believed to be (partly) descended from Romans so I think accuracy might have been intended from the get-go here and they just missed.

Keep in mind this was the 80s, you couldn't just look this stuff up on the internet back then and writers (which the game devs would be in the context of naming a character regardless of your opinion on Castlevania's narrative merit) can only be as good as their sources when it comes to real-world accuracy.

Christopher Belmont - クリストファー・ベルモンド (Kurisutofaa Berumondo) and Soleiyu Belmont - ソレイユ・ベルモンド (Soreiyu Berumondo)

Christopher is an English spelling of a biblical name which has a zillion different versions which クリストファー could believably be, but I know of no Romanian version. Some eastern European alternate spellings that could still be katakanized the same are Krisztofer (Hungarian), Kristofor (Albanian / sometimes Croatian), and Khristofor (Russian).

Soleiyu is probably meant to be Soleil, but I have no idea. It's not really that common of a name at all, but it's the French word for sun. Maybe Krisz is a hippie or something, for the Watsonian perspective - and a dev probably just heard it and thought it was a nice name, for the Doylist.

Trevor Belmont - ラルフ・Ｃ・ベルモンド (Rarufu C Berumondo)

Rarufu is, as most people know, Ralph. This is the English (and German, and Swedish) form of the name Radulf, and the Romanian form is Raul. If you wanted to stretch a bit, you could also imagine Ralph as a nickname for someone named Rafael, which IS a Romanian name.

Trevor is English or Welsh.

No one knows what the C stands for, so you can pick something out for yourself if that sounds fun to you. FWIW, I've heard middle names aren't really a thing for Japanese naming conventions, so just shortening foreigners' middle names to the initial and leaving the rest as katakana happens sometimes.

Sypha Belnades - サイファ・ヴェルナンデス (Saifa Verunandesu)

It's well known her name got unbelievably butchered in the katakana spelling and translation process. Belnades was most likely intended to be Fernandez, a Spanish surname. Sypha is sometimes translated instead as Cipher, a reference to her hidden identity. This might've been the authorial intent.

Sypha's first name has the same katakana spelling as Seifer Almasy from Final Fantasy VIII, whose name most likely comes from the arabic name Seif. I find this potentially interesting, since if we presume she's Spanish from her last name, much of what is now modern-day Spain was still Muslim in the 1400s.

Alucard - アルカード (Arukado) AKA Adrian Fahrenheit Ţepeş - アドリアン・ファーレンハイツ・ツェペシュ (Adorian Faarenhaitsu Tsepeshu) AKA Genya Arikado - 有角幻也 (Arikado Genya)

Surprisingly, Alucard gets out with his name fairly unscathed in terms of translation. The main thing is that ţepeş means impaler in Romanian, and is not an actual surname.

Alucard is Dracula backwards, and don't pretend you're unaware. It's Castlevania's Nina Tucker.

Fahrenheit is a German surname.

Genya is a Japanese name that traditionally means "well born", but Genya's kanji spelling here is different. The spelling 幻也 basically means "illusion". He's barely pretending to have a secret identity lol. Apropos of nothing, Genya is also a shortening of the Russian names Gennadiy or Yevgeny.

Arikado is, yknow, one sound off from Alucard. 有角 means "horned".

Changing one's name to or even just going by a Japanese name with kanji spelling after becoming a naturalized citizen of Japan is pretty common, but it's not a requirement for citizenship.

Grant Danasty - グラント・ダナスティ (Guranto Danasuti)

Grant is English or Scottish.

I've seen Danasty presumed as a mistranslation of Dynasty or some variation thereof, but in my personal opinion it's probably taken from Dănești. Doesn't necessarily mean Grant is royalty or anything, it's just a name the devs would've been way more likely to see in a book and thought of as an interesting one to use.

Richter Belmont - リヒター・ベルモンド (Rihitaa Berumondo)

Richter is a German surname. He was named after the conductor Karl Richter.

Maria Renard - マリア･ラーネッド (Maria Raaneddo)

Maria is an extremely common name throughout Europe. It is used in Romania.

I've heard Renard may be a mistranslation where it was meant to be Renardo. Renard means 'fox' so it fits her animal motif, which may have been the thought process of the translator or the devs. Renard is an English name.

Eric Lecarde - エリック・リカード (Erikku Rikaado)

Eric is indeed a name used in Spain.

Lecarde is a glaringly obvious mistranslation of Ricardo, a Spanish surname. He even has an R on his crest!

John Morris - ジョニー・モリス (Jonii Morisu)

John is an English/Dutch/Danish form of Iohannes. Other forms throughout the world include Jack, Ion, Ivan, Ian, et cetera. In Japanese he's called Johnny, but I suppose the translators thought John more suitable.

Morris is, of course, after Quincey Morris of Dracula fame. Surname can belong to one of English, Scottish, Welsh or Irish paternal descent. Worth noting is that two other characters from Dracula, Jonathan Harker and John Seward, have variations of his first name as well.

Sonia Belmont - ソニア・ベルモンド (Sonia Berumondo)

The writing in her game sucks, but Sonia is a Romanian name! So she wins some points back for that.

skipping the 64 games and Circle of the Moon for now.

Juste Belmont - ジュスト・ベルモンド (Jusuto Berumondo)

Juste is an aggressively French name, but the Japanese transcription presumes an incorrect pronunciation. The 'J' should be pronounced as a 'zh' sound. Strangely, I don't think there are any major Eastern European languages that have the 'J' sound like in ジュ, either, so god only knows where he got that from in-universe if we presume the katakana pronunciation is correct. Personally, from now on I shall be pronouncing his name as Джюст. (For what it's worth, Romanian used a cyrillic writing system until the 1800s.)

Lydie Erlanger - リディー・エルランジェ (Ridii Eruranje)

Lydie is a name that's used by both the French and Czechs.

Erlanger may be a locational surname from the Bavarian city of Erlanger. Maybe she's Transylvanian Saxon on her dad's side?

Maxim Kischine - マクシーム・キシン (Makushiimu Kishin)

Maxim is a name originating from Russians, Ukrainians, Belarusians, and Czechs.

Kischine is likely a pun on Kishin, but given the locational naming convention for Lydie, it may also serve a dual purpose by alluding to Kishinyov, the Russianized name of Chișinău. Chișinău is a Moldovan city which was occupied by the Russian Empire in the 1800s. In Harmony of Dissonance's time, it was under the Principality of Moldavia, but a locational name based on the city may have been changed to a Russianized form by immigration at some point in his family's history.

Soma Cruz - 来須 蒼真 (Kurusuu Soma)

Japanese name. 蒼 (so) - pale/blue, 真 (ma) - truth.

While Kurusu would be the 'correct' way to write his name in English, according to a dev interview translated by Shmupulations, Cruz was chosen for localization reasons and is after the Spanish actress Penelope Cruz.

来 (kuru) - come, 須 (su) - must.

Julius Belmont - ユリウス・ベルモンド (Yuriusu Berumondo)

Julius is a widespread name. His name is pronounced with a 'J' sound in some voice clips of Dawn and Despair, but in katakana it's a Y sound (as it should be). The Romanian form of Julius is Iuliu. His alias being "J" suggests that his name is actually spelled with a J, though. Y-pronunciation with 'Julius' spelling exists for Czech and Lithuanian, or it could be the Polish 'Juliusz' or Slovak 'Július'. It's also possible he changed his name at some point, or that the 'J' spelling was chosen for when spelling his name in the alphabet if he was born in a country that used cyrillic. Part of former Romania was annexed into Soviet Ukraine in the 40s, so it's possible!

Yoko Belnades - ヨーコ・ヴェルナンデス (Yooko Verunandesu)

Yoko is a Japanese name with varied meaning depending on the kanji used. However, her name is spelled in katakana. This is somewhat common practice for people who were not born in Japan or who were born there but do not live there anymore.

Her last name being in katakana makes sense, though, since her last name is still Belnades/Fernandez, which isn't a Japanese name and doesn't have kanji to begin with.

Leon Belmont - レオン・ベルモンド (Reon Berumondo)

Leon is a far-spread European name. Of eastern European options, it's used in Poland and Croatia. For what it's worth for the Polish possibility, the only relic in his game you cannot beat the game without is the Svarog Statue, and Pomerania (which makes up a small chunk of modern-day east Germany and a larger expanse of northwest Poland) wouldn't be fully officially Christianized for another 30 years at that point.

Sara Trantoul - サラ・トラントゥール (Sara Torantuuru)

Sara is an extremely widespread name, including in Romania.

Trantoul is, as far as I can figure, French.

Mathias Cronqvist - マティアス・クロンクビスト (Matiasu Kuronkubisuto)

Mathias is a widespread name.

Cronqvist is Swedish. The game also appears to take place in Sweden.

The similarity of his name to that of Matthias Corvinus is most likely intentional.

Rinaldo Gandolfi - リナルド・ガンドルフィー (Rinarudo Gandorufii) and Justine Gandolfi - ジュスティーヌ・ガンドルフィー (Jusutiinu Gandorufii)

Rinaldo Gandolfi's first and last name are both Italian.

Justine is a French and English name.

Celia Fortner - セリア・フォルトゥナ (Seria Forutuna)

Celia is a Spanish and English name.

Fortner seems like it was meant to be Fortuna, which is a Spanish surname.

Dario Bossi - ダリオ・ボッシ (Dario Bosshi)

His name is Mario Rossi, Italian version of John Doe, with the first letters changed.

Dmitrii Blinov - ドミトリー・ブリノフ (Domitorii Burinofu)

Dmitrii is a less common form of the Russian name Dmitriy. They're pronounced the same.

Blinov is an extremely uncommon Russian surname. "-ov" at the end of a Russian man's last name (as opposed to "-ova" for women) is roughly the equivalent of the "-son" ending in English names like Jackson, Johnson, et cetera. "Blin-" comes from blini, a Russian pancake. So, it basically means, "son of Pancake." I didn't think it was a real name for the longest time, but apparently a few very unlucky souls have borne this name throughout history and done stuff to earn themselves Wikipedia pages. I salute their strength of character to not kill themselves over having such a name.

Hector - ヘクター (Hekutaa)

A name of Greek origin which is otherwise only really common in western Europe.

Completely irrelevant, but when you combine the names "Henry" and "Victor", the two first names Frankenstein is known by (Henry in film and Victor in the original book), you get "Hector". With Hector's devil forgemaster status, this is potentially interesting.

Rosaly - ロザリー (Rosarii)

A misspelling of Rosalie, a western European name. The Romanian form is Rozalia.

Julia Laforeze - ジュリア・ラフォレーゼ (Juria Raforeeze)

Like with Julius, Julia is a very far-spread name, but eastern European versions of the name use a "y" sound where the J is. Julia's name is pronounced with the J sound.

"Rafforza" means "to strengthen" or "to reinforce" in Italian, and given Julia's place in the story, this was probably the intention.

Isaac - アイザック (Aizakku)

A common name throughout western Europe and some of eastern Europe. Just like how Julia's name should've been spelled as Giulia if she were Italian like the surname suggests, the Italian spelling of Isaac's name is actually Isacco. This would be katakanized differently too.

Pretty much same as his old man, except Jonathan is the actual, exact same spelling as the Dracula character Jonathan Harker.

Charlotte Aulin - シャーロット・オーリン (Shaarotto Oorin)

Charlotte is the first name of Bram Stoker's mother. Western European name.

Aulin was frequently translated as Orlean in promotional material up until the game's release. Aulin might be a corrupted locational surname from Orléans, France.

Shanoa - シャノア (Shanoa)

Shanoa is a codename, and her actual name is unknown. "Shanoa" is a corrupted form of the French words "chat noir", meaning "black cat."

Albus - アルバス (Arubasu)

Albus is presumably also a codename. It's the alchemical term for the process of whitening a substance.

Barlowe - バーロウ (Baarou)

An English locational surname.

A Russian or Bulgarian name. The Romanian forms are Nicolae or Neculai, which are pronounced differently and would be katakanized differently.

Abram is an English name. However, the katakana using the character for "vu" rather than "bu" suggests the spelling should be Avram, a Jewish name that is used by Jewish Romanians.

Ion is the Romanian form of John. Aeon doesn't really exist as a name.

Anna is a widespread name throughout both western and eastern Europe, and elsewhere. The Romanian form only has one "n" usually, which would've been spelled in katakana as アナ and not アンナ.

A widespread name found all over eastern Europe with rising popularity in the west today. It is used in Romania.

A Romanian (among others) form of Eugene. The katakana spelling is using what seems to be the German form of pronunciation, though.

A Romanian name. The katakana is pretty strange.

A Romanian name. Common in Russia, Bulgaria, Macedonia, and Estonia too.

A Romanian name. Common in Poland, the Czech Republic, and Slovakia too. Some western Euro countries as well.

A Jewish name that's also found in many goyische western European cultures. Note the "Y" pronunciation of the "J".

A Romanian name. Also common in western Europe.

Serge is an English form of Sergei. From the katakana I'm guessing they meant the Romanian form Sergiu.

TBA: Laura 1&2, Stella and Loretta Lecarde, Carmilla/Camilla, Dracula, Walter Bernhard, the COTM and N64 casts