Kotlin Libs not working, modrinth and curseforge don't recognize them, and the correct version required (5.0.2 and 5.1) are archived and for incorrect versions.

[IAmB34N]

https://mclo.gs/uvIGp7I

[thedarkcolour]

I have many questions...

• what mod is "generating jar with updated Kotlin"
• why are you using such old versions of KFF

Those versions are archived because they have known problems. I suggest using an actual up-to-date version of KFF.