Something I've found that works, with mountain formation, while I've been dinking around and modifying your own methods to some of my own (your method for mountains is way simpler than what mine was, mine was a sort of clone stamp process, but not as eloquent as some of the others in tutorials.) The erase tool set to a spatter brush at around 45 pixels, give or take per needs, put to flow and opacity 100% can be used to modify the mountain body itself, after your click method, to work possible valleys, passes, and some other terrain features. Basically painting back in the 'flats' before adding in the high and lowlands. I've also found a basic airbrush blur at Normal and 50% strength can help in soft tweaking some of the peak lines in the middle as well as along the click texture. As you can see here.

Click image for larger version.  Name: Mountain tweaks.jpg  Views: 545  Size: 192.8 KB  ID: 50995

It's subtle, and as you can also see I've been fingerpainting with the high and lowlands to make some tests with passes (need to narrow them canyons m'self) and a bit of a basin that will likely be turned into a desert. I use a Wacom tablet more than raw mouse, so that would have some added difference to it as well, so that changes the texture as well, and I've been experimenting with both mouse and tablet. But thought some folks might find this little example of what I've been discovering helpful in addition to the plethora of work RPGmaker has done.