I now have the app, so I’ll weigh in a bit more now
I don’t know that I’d add every single playlist (especially since I don’t know if they’re static or not, maybe the character playlists tho?), but I would at least add the game releases, including the extended recordings somehow
it appears they do send out announcement notifications with each game release, so that might make it slightly easier to add release dates
as for the artist fields, I’d say credit them to the composers (if known), or to Nintendo (if not known), following the soundtrack guidelines