Guide on adding a new model, animation, and creature to HoMMV

Here, that's a completely different matter. I haven't encountered this problem myself, and even if I had, I might have overlooked it because it's such a minor issue. It's good that you noticed this bug. Are you sure the problem is specifically with the UV mapping? Maybe while you were fixing the UV mapping, you accidentally flipped the normals in the wrong direction? It's just very strange and unclear why the UV mapping would cause such a problem. I recently exported a model with a completely broken UV mapping (everything was compressed into a few vertices), and there were no problems with the polygon display.