Here are two 3D platformers I haven't really heard a lot of but still had very fun with last year.
Demon Turf - 335 Reviews What pulled me in initially was the art syle, the games looks a bit like the cartoons from my childhood. This one got combat, exploration, bosses, collectables. A bit of a problem is that the game tried to do a lot of things at the same time, resulting in a bit uneven quality overall. There are also leaderboards if you into speedrunning.
Demon Turf: Neon Splash - 105 Reviews Some kind of standalone DLC/spinoff to the first game. In this game everything is more streamlined and the design feels more focused. Combat have been cut in order to give the platforming more time to shine and a reason to simplify the controls. The focus is on repeating the same levels for better a time on the leaderboard. Speedrunning is not really my thing but I still found enjoyment in the game. Much cheaper and short than Demon Turf.
Looking through the JRPGs I own, most of them with adult cast are western made. Depending on how far you go with j-influenced some might fit on your list. Zeboyd games is a western studio making JRPG like games with their own twist on them. Cosmic Star Heroine have a completely adult cast. Been years since I played through the Cthulhu games, but I remember the cast being mostly adults in them.
CrossCode from Radical Fish Games stretches what I consider a JRPG to be, but it still comes up in my library when searching for the tag. I think most of the cast were young adults rather than children.
Fell Seal: Arbiter's Mark by 6 Eyes Studio is pretty much a Final Fantasy Tactics.