I posted a comment on the mod page, but figured I would post one here as well.
The 1.14.4 beta version out right now doesn't work with Optifine. I've tried all the versions of Optifine for 1.14.4 and none of them work with Better Foliage.

I have the same issue with 1.12.2. The game will load with optifine. But when you start up a world it immediately crashes. Better Foliage and Optifine are not friends right now Lol.

I'm using 1.12 and the latest version for 1.12 will not work with any version of Optifine I try, E3, F4, F5, doesn't matter. Reverting to old version works again.