Inside the folder find and open the file gbuffers_terrain.vsh in a text editor
Near the top of the page (line 17) find the line that says #define ENTITY_LEAVES 18
Replace 18 with the ID of the TFC+ Leaf Blocks. Note: ID numbers may be uniquely generated per installation or per world. If you have WAILA installed, you can place your cursor over some leaf blocks to see the right ID number.
Save the text file.
(some) TFC+ leaves should now be recognized by the shader.