Hello, could you please write documentation for Kotlin? Otherwise, it will be very difficult for beginners to learn how to create projects in Kotlin.

Minecraft is written in Java. So the main development language will be Java. Any development planning to use Kotlin is required to know Java well enough to translate them to Kotlin.

Not to mention that Mixins cannot be written in Kotlin so if you're planning on using Kotlin, knowing both well enough is required.

You can always ask for help in the Fabric Discord.