I just checked the battle brothers files structure, and sadly most of everything seems to be completely hardcodded.
I would like to ask you to export as much of your game as possible to .txt files and organize it in such a way that modders could easily access and modify them.
For example i have a bunch of rebalance ideas for weapons and items, but i dont think i can currently change any items properties. The more you let people tweak with your game, the less they will bug you to tweak various stuff, specially when it comes to all those “bad” ideas youve probably heard hundreds of times before :)