It seems that there are many users with problems. Sorry.
I did a clean install with the mod just to make sure there were no problems and I could finish the game twice with no artifacts or flickering textures or lack of it anywhere in the game.
It is difficult for me to retire to "test my work more" because it is tested and I have no such problems. I'm not sure if it's a matter of drivers, graphics cards brand or other problems.
I will try to find out but I will need cooperation of the people who do suffer from these problems.