I've been trying to get world edit to work with cubic chunks, a mod that allows terrain generation and destruction above the normal minecraft y-values. I've managed to load worldedit together with cubic chunks but I can't seem to destroy not place any blocks using world edit when y<0 or y>255. I'm using Minecraft 1.12.2 with forge.
I know there's an old mod (Worldedit XT) that makes the two work together but the mod is really out of date. (1.4.4 - 1.7.3)