Big fan of the project and have used it for a while!
I have recently migrated a project to 5.5 and decided to take a look into HammUEr again. One thing popped up:
It seems normal generation for brushes is behaving strangely? Tangents and normals don't seem quite aligned as expected, which makes materials that have normal maps shadow incorrectly as the tangents/normals for certain corner vertices are not quite correctly oriented for imported brushwork. I've simply disabled normal maps in materials so the shadowing problem isn't evident in the imported brush meshes.
I wanted to take a look at the issue, but since I mostly use HammUEr for fun side projects, I don't really have a lot of time to dedicate to fixing the bug myself.
I'd happily contribute/donate/commission(?) a fix though, such that they can be prioritized and so other folks can take advantage as well.
Cheers!