I tried the Alfheim 1.6 Dev 2 version of the mod with the latest version of Forge for 1.12.2, and I managed to load into the title screen, but when I tried to create a new world, it crashed and gave me this:
Crash Report: (https://mclo.gs/IbeS9lA)
Latest Log: (https://paste.ee/p/Pg9gL8hO)