I had a look recently at your map and those mountains". Here's my 2 cents:

- use wilbur to get some erosion, if you have the time, do it in small steps in small areas at the time, so that the entire map doesn't look too homogenous,
- between every few steps in Wilbur software, go back to your painting program and add a little more white paint in the mountainous areas

This will make your heightmap much more believable, as it will have rivers and valleys and much less randomness. Also, plateaus are also allowed to exist, don't draw linear ridges only.