I never played any Castlevania, so any reference to that I will not get As for accents Hellsing family is English, the setting is England, Seras is English as well, so it makes sense to have some English accent for her. That being said, English is not my native tongue and neither is Japanese. They are the same as related to me, foreign languages. So it never made sense to watch anime in English for easier, more natural experience. If I have to watch it in a foreign language, I would then rather do it in original. Plus I've been reading subtitles on TV since I was 5. Everything foreign was subbed, so I never encountered difficulty in reading subs and watching, as many of my English and American friends did. They often complained about it, not being able to follow a video and read subs at the same time. For them it made a lot of sense watching it in their native tongue. So I never encountered that cockney accent. Plus Alucard's japanese voice is deep, sexy and menacing. A perfect fit. I think it's way nicer than english one (I've heard some clips of it).