I've been trying to have Botania's mushrooms generate in the Misty World using tweaker mods that can do decoration functions, but it currently cannot work, seemingly due to a lack of Forge events being fired upon doing your worldgen. Specifically I've tried using both BiomeTweaker and CoFHWorld to accomplish this.
This is similar to https://github.com/Liahim85/MistyWorld/issues/38 but as yet it still seems to not be implemented which limits a bit what pack devs can do with the mod to integrate others with it.

Thank you for message.
It seemed to me that I added events. Perhaps not everywhere. Or something went wrong.
I will try to fix it in the following updates.

Added Pre & Post Event to BiomeDecorator.
Will this solve the problem?
https://cloud.mail.ru/public/Jma9/2VUSxZ318

Update & Close

Just tested and that does seem to be working