https://en.wikipedia.org/wiki/Nintendo_Software_Technology
They also make quite a few more changes than expected when localising games. Or at least they did in the olden days, where the American versions of games sometimes had different/extra features compared to the Japanese originals.
I think some of the localisation team are also regular voice actors for the games, on a worldwide basis.
Oh, interesting! The list of games isn't particularly impressive though, a lot of ports and remakes. Compare that to also-US-based Retro Studios, which isn't considered under Nintendo of America from what I understand.
It's not just localization and marketing they do have corporate IT and some development/studio as well as very poor security policies that gets them breeched every now and again which makes sense, they pay poorly and from my personal experience gatekeep but that makes sense from the applicants that probably get in their applicant pool.