Nomura might not speak English, but there are people near him who do, like Yasue. Obviously they're busy working on a bazillion games at once at all times, but it's worth it in the long run for the localization team to put in the effort for as accurate a translation as possible.
Though honestly, it feels like SENA just doesn't care that much about KH. Not even just about translations, but merch and advertising, even stuff like voice direction or audio quality is completely up in the air with this franchise.
KHIII was the highest-selling KH ever, and somehow Jason Dohring sounds like he's being microwaved in Re Mind.