I like your continent shapes (and that's often the hardest part to make feel right!), but I think that the mountains are perhaps too uncorrelated to the main continent shapes and thus feel a bit tacked on. I think part of that is that it looks like whatever selector or clamp you're using to get the continent shapes is producing basically what looks like a flat table for each continent, that the mountains are then being added on top of.
Modulating that underlying surface height of the continent (before mountains are crafted atop it) I think would go a long way.
Also, it might be easiest to start with creating mountains that look like what you want in isolation, not worrying about connecting them to the continents yet at all. Zoom in and make sure they look the way you want. Once you have that, then you can add or choose them into your scene and worry about how to blend or place them.