it is a GDNative library for handling projectiles and stuff..
The code inside BaseObj.gd contains something that uses tbfg.dll called FGObject and also FixedMath..
Though it's made with godot-rust which is going to be tough..
Also tbfg actually stands for "The Best Fighting Game" and FGObject by this definition probably in my guess stand for "Fighting Game Object"
Also do you have Discord? I would love to chat about this!