@acraigl
I don't have a great answer for you. Specifically for GLideN64 there is a source code repository I have been checking since the project lead gonetz said a new version is imminent. It actually was just published as a specific 2.0 release yesterday. Still has some regression issues like Mario64 though.
GLideN64 code repository blog
Not sure how active mupen64plus or glupen is for actual emulators.