We've had this discussion before whether we should use Castlevania or Akumajou Dracula and it was decided to use Castlevania. Using the Japanese spelling for the characters was inconsistent given that we intentionally use the localized English names for the copyright tags.
I can hardly argue with site's owner, but you already have at least one example of such inconsistency and pretty big one at that: it's Pokemon once again.
Most games in the series spell out full "Pocket Monster" in its name and all official promotion materials in Japan, but English market overwhelmingly uses abbreviation "Pokemon". So you already do intentionally use the localized English names for those copyrights and still use original Japaneses name for trainer characters. I don't really see many people complaining about that and I don't even see this inconsistency as problem at all.
Remembering that, once again, ralph_c_belmondo tag was alive for more than a decade I don't think it really bothered anyone either until a month ago.
-----
If you want to make an alias request for Belmondo -> Belmont then I'll approve it. If there's some difference between new/old Trevor and they shouldn't have the same tag then we can talk about how to split the tag up. I'm not familiar with this character so you're going to have to explain what the difference is.
Good. I'll put up the request.
Relations from original story are common knowledge by now, so I won't hide them:
Dracula
His human wife: Risa / Lisa - killed by humans, and that's why D doesn't like humanity much
Their son: Alucard - that's an alias, real name Adrian Tepes, his another alias arikado_genya implicates alucard_(castlevania) on danbooru.
On Vampire Killer side:
Vampire Killer of 15th century: Ralph (ラルフ/Rarufu) C. Belmondo / Trevor Belmont
His wife: Sypha Belnades
Distant relative: Simon Belmondo / Simon Belmont - Vampire Killer of last half of 17th century, great-grandson of Christopher Belmondo who is great-grandson of Ralph above
Ralph works with Alucard to defeat Dracula. Simon only meets Alucard briefly once (or twice if you count not-sure-if-canon game).
In LoS (not hidden because this is info from promo/prologues):
Vampire Killer of 11th century: Trevor (トレバー/Torebaa) Belmont (without C. and actually "Trevor" in Japanese release)
Still his wife: Sypha Belnades (married into Belmont)
Suddenly their direct son: Simon Belmont
Now for Dracula's family and it goes behind the spoilers as it is heavy part of story post LoS1:
Dracula: is actually Gabriel Belmont, protagonist of LoS1, he assumed this alias after he became a vampire in post game DLC
His wife: Marie Belmont - killed by Gabriel himself though he was controlled and doesn't know that until much later
Their son: Alucard - that's an alias, real name - our new Trevor Belmont of LoS again - he's son of Gabriel and Marie, arikado_genya doesn't apply to him at all
Trevor(LoS) can't work with Alucard(LoS) because he is Alucard himself. Simon now works with Alucard, his own father, instead. Gabriel/Dracula is now first Belmont and Simon is his direct grandson, instead of being distant relative of Leon Belmondo.
As you can among those six loosely matching characters, 2 characters are actually merged into other 2 in LoS and then everything is heavily shuffled. This, obviously, invalidates pretty much any possible tag aliases or implications that would exist on original characters. Only Sypha is remotely the same, but any family tags except wife+husband for Trevor would be invalid either for LoS or classic incarnation if you keep them as single entry. Dracula(LoS) now implies Gabriel, when original doesn't. Alucard(LoS) is not implied by Arikado and subsequently Trevor(LoS) is not implied by Arikado either. Any family tags on all listed characters won't match between classic and LoS except that wife+husband again. Alucard(LoS) implies new Trevor(LoS) but NOT old Ralph/Trevor(Classic). Alucard(Classic) and Ralp/Trevor(Classic) on same image will increase sex count, but Alucard(LoS) and Trevor(LoS) will need alternate_persona instead and will carry implication anyway. None of LoS characters have any relation to Dracula(Original) and Risa/Lisa.
Those six characters above are most spoilerific and differ most between classic/LoS as of now, but since the rest of the story are heavily tied to them I'm pretty sure every future LoS character that shares name with classic will be different too because of relations to those and should be tagged separately from the start. So far it is really only recurring bosses whose names and lore come outside of Castlevania. Fan wikis use separate pages for classic/LoS characters too since not only entire stat/relation/summary box would be different between them, you'd simply have to list two different stories/timelines/hell, everything for each incarnation.