It appears that EnumHelper was accidentally deleted in this commit c4cf950863256ed048a46e098401a969dfe4cb2e as it is still used in RuntimeEnumExtender.
It was not accidental, we just need to resurrect that one method and place it elsewhere.
I have a proposed patch here: https://github.com/tterrag1098/MinecraftForge/commit/f86551a9835d065cbb0f2d5ef4d0ce9586c1d844
Just waiting on approval of my implementation (I'm not 100% sure this is the intended use case of UnsafeHacks)
Edit: take 2: https://github.com/tterrag1098/MinecraftForge/commit/0d1a2f2af343bbd6907a74607ff156eefa6cfcc3
Is this resolved now?
Yes, fixed via 0d1a2f2af343bbd6907a74607ff156eefa6cfcc3