As for Heroes 6, I was also disappointed. The graphics are idiotic, everything was redone, etc... Yeah. But I haven't encountered any problems with textures or transparency. No one has mentioned it either; everything seems normal. I think it's worth asking other players who have downloaded the game; I don't have any problems. Maybe your game version is different?

I just downloaded it and took a look at the dungeon in the editor. Honestly, I didn't see anything wrong, meaning that everything isn't blurry. Either something is wrong with the editor, or there's a glitch in the map itself. Just in case, it's better to double-check.

And regarding transparency, it's possible that I was referring to those texture duplications, where the terrain under an object is uneven. Usually, such errors are reported in the message before saving the map.