As you can see, trying to edit the landscape results in a very blocky look. I’ve tried various settings when creating the landscape and using the sculpt tools, but so far this is the best I’ve gotten. Is this really the highest landscape resolution UE4 can have?
UE4 does not constrain landscape resolution. It only imposes limit on the size of the height map you can use. If your number of vertices per meter seems low to you, downscale your terrain while keeping heightmap resolution the same.
The XYZ Scale values also will determine how much resolution you have while painting.
You may have to rescale the Y (height) axis of the heightmap in order to use a better engine landscape scale value to allow for finer painting vertex adjustment.