Board Thread:LotR Mod Technical Support/@comment-75.110.43.167-20181108154232/@comment-27219153-20181108165638

The Mod uses a different biome system than vanilla, meaning that the Mod and vanilla biomes (as well as modded biomes using the vanilla biome system) can have the same ids and never cause an issue.

has issues with twilight forest, but only in combination with chisel.