Hehe, this is one of the great problems of the -mod build; getting vegetations into the build is bloody difficult. I think the basic process is that the vegetation.db is not recreated using the -mod build files. To get the new vegetation in you have to put the files into the vanilla data folder, create the new vegetation.db from a vanilla game and then put that new vanilla vegetation.db into the mod folder, along with the vegetation data files as well.

Foot