I realized it hasn't been mentioned: The recent big Nintendo leak included several unreleased translations for Gameboy games. I can't link to them, but there's a list of which games leaked were duplicates of retail titles, new region releases, and new translations (If you got the dump with weird file names, they really are just .gb files under a different name)
https://docs.google.com/spreadsheet...C0aST5t7M_JZegdOrbUyYc6_I/edit#gid=2112430196
Most of the new translations are non-English or crappy sports games, but ones I'm aware of
Chikyuu Kaihougun ZAS (As ZAS. Not that interesting since it's a autoscroller shooter with English menus already.)
Legend of the Sea King (Legend of the River King spinoff, actually the second game in its spinoff series. Actually got some advertisement in US despite getting canceled)
Little Master: Raikuban no Densetsu (As "Doomsayer: The Hero's Crusade". Already has a fan translation.)
Ninja Spirit (There's better ports of this and no meaningful text so meh)
Gargoyle's Quest 2
Robopon Star (Only Sun version was released in English. Menus are way smoother and text speed much faster, which indicates it was likely made after Sun was released in the west. Unfortunately not playable on most emulators right now due to Robopon using an obscure save type and RTC hardware that isn't getting auto-detected.)
Supershot Golf Robot (Falls under crappy sports games, I've actually played this one and it's pretty bad even by golf game standards. I mention this for the sheer absurdity of the US translation which changes it from a bog standard golf game to some plot about defeating robotic overlords with the power of golf. Also an European version as "Golf King" with English text and none of the other changes)
X (as Lunar Chase)