Hmmh,
not sure what I did last time when testing … I re-created the DWG Upload.
Now DWG Hierarchy, Grouping by Layers looks totally ok, great.
Also I can see Object/Layer Colors for DWG now - in Shaded Mode (not Rendered)
I am pretty happy with this so far.
But I think I need a clean DWG File for further testing. That old file contains too much early legacy objects, which don’t behave well even in Bricscad …