Thanks for the patch.
Tool tips on the instanced values would be nice.
The problem with the texture is not with the edging but with the tendency of the material applied to river and waterfall to act like a magnifying glass.
There is not a “river_water_b”. I assume you mean river_flow_b or river_flow_a?
A few suggestions.
Love the trees in the demo scene and you could add value by making a few prefabs.
I’ve been copying a few of the ready made’s into my level and modifying to fit so a few component BP’s would be a nice touch.