RTF is a global modification that replaces all towns in the game.

I tested it – I only encountered this bug recently (4 golems in different Dungeon creatures were supposed to trigger it)
Now I want to run tests in the game; there might not be such a bug there (I hope).

It exists. It's especially noticeable during sieges. When I was testing those creatures, I was very surprised to see that my army was periodically half black. As a result, I stopped using gloss. And I advise you to do the same.)
You can achieve a similar shine effect using the base texture; it will be slightly worse than gloss, but at least without the ugly bugs.