Speaking through the lens of a native speaker of a foreign language working in Japan, my experience is that most companies don't usually go as far as hiring a part-timer to check short texts in non-Japanese languages for consistency, since they usually think "it's not that important" and see those things more as giving it a "foreign flavor".
But of course, taking into account the kind of game FGO is and that now they can't delude themselves thinking that native speakers of almost every language will not see (and laugh at) these NP names, I do think that at this point they really should have someone in charge of this. I'm not saying someone who knows every language used in the game, but more like a coordinator that can check these with native speakers, hiring them as freelance consultants for example.
Sadly, you'd be hard-pressed to justify all that effort and money in front of your typical Japanese boss, so what usually happens in the end is that when they feel like having them checked, they resort to foreign employees without a translation background who happen to be there, "my friend who's totally fluent in this language" and so on, because that's free. And if there's nobody who knows the language at hand, they'll probably not go out of their way to check it.
Sorry for being so cynic: again, that's just my personal experience. Maybe they do have a coordinator and the problem is that some consultants have higher language skills than others? We'll probably never know.