I think they should work on the transitions.
When the land meets the rivers, when the land meets the cities, these borders seems not well finished, they are too abrupt.
Also the map needs texture variety. All looks the same everywhere.
But one of the problems is the comparison with Kuban, and here there is something to be said.
Kuban has topographically, geographically speaking, much more variance and that interferes a lot in the perception between the two.
Rheinland is mostly flat ground and there is not much to do in this regard.