I may be blind, but searching the web I can't find any basic information about modding this game, beyond the "Example Mod" which comes with the game and is empty. Looking at published mods there seems to be some xml header lines that indicate that a given file is intended to modify the standard file - presumably on a leaf node by leaf node basis. What are the other options, and how would I indicate them? Can I replace a non-leaf node without replacing the entire tree it's in?

I see some "mod tools" here in this forum, but the GitHub link goes only to source code, no releases. I don't have a compiler installed on my home gaming machine, so that's not very helpful either.