Hello,
The NeoForged project just released their latest version, cutting down the cross-compatibility with Forge.
Are there any plan on supporting them?

Thank you!

Yes, I hope to have a version ready by the end of the week.

Looks like there are still a few issues in NeoForge that prevent language loaders from working. I can't say when KFF will support NeoForge, but for the meantime there seems to be no "minecraftLibrary" configuration in NeoGradle and NeoForge doesn't seem to detect the IModLanguageProvider service.

I assumed it was no easy task. They went crazy on the rewriting...
I guess your issue with NeoGradle is a "bug": neoforged/NeoGradle#12 .
Have you tried using their remapping script (https://gist.github.com/Technici4n/facbcdf18ce1a556b76e6027180c32ce)?
I see the mention of IModLanguageProvider in it, so I guess it must have changed in some ways.

I can't wait for your library to be compatible. I really can't stand Java and your good work has been a life saver.
If you need help from another software developer, I'm at your service ;).

Done. Kotlin for Forge 4.6.1 now supports NeoForge. Make sure you are using kotlinforforge-neoforge in your build.gradle and not kotlinforforge in your dependencies block.