This is really awesome. The dev explains it's like Proton on Steam Deck so that should give you an idea of how it works. It's translating from one type of code to another. You need to figure out how to translate every little individual code, but after that, you can translate anything in general that uses those codes. They also mention having to manually translate special game-specific code, since that can't be generally translated.
It seems like the key thing here was to get accurate behavior, which requires fully understanding all the original codes. The manual Zelda decompilations did most of the work for that, so the Zelda games are still the most complete examples. But other games can reuse that work as long as they don't do anything too special.
_foolmo_
he says listen to my story this maybe are last chance