Yeah the names are a little odd in the series and I don't think the official primary translations are accepted as accurate by some in the community, at least for certain characters. Ceras/Seras/Ceres is one I've seen as is Walter's last name (Dornez? Dolnez?) and Integra's first (Integra, Integral?**). Of course sometimes people are just being stupid, like insisting Alucard should actually be Arucard because that's how the Japanese pronounce/spell it. Making it worse is that I've seen official translations for various merchandise use many of these conflicting translations, including "Arucard".
Of course sometimes it's hard to tell where funky translations end and purposeful decisions begin. Take Integra(l)'s title of "Sir". Technically if she's Knighted her title should be "Dame", and I think that would also be true if she were a Baroness, which she may be. But considering her traditionally masculine personality, appearance and job it's not unthinkable that she would choose to go by "Sir" rather than Dame. Or it's possible Kouta Hirano just didn't research that part very much. So who knows.
**If the latter translation is true does it stand for something? She's "Integral" to what? The Hellsing organization? Alucard? The plot itself? And if it's supposed to be "Integra" is it a corruption of "Integrity"?