It appears that my implementation of brightmaps being automatically deactivated for redefined textures in pwads did not work. This is not a bug within the pack, but GZDoom.
It has just been fixed and should work as intended in the next GZDoom release after 4.2.4 (presumably 4.2.5).
While we are at it: How do you guys feel about the
pods in Heretic using brightmaps? I just noticed recently they glow in the dark and I am not sure if they should. Since they are explosive it can be useful so see them (to avoid hitting them with weapons accidentally), but the question is whether it looks right since it's some kind of bush which probably doesn't glow usually.