Hey WixZ, the setup worked perfectly in order to select the different heightmaps for the displacement, thanks a bunch! 
I’ve got one last issue with the displacement though: the erosion layer has pebbles in it, and is supposed to pop with the tesselation, but that’s not happening. Instead I’m getting “spiky” edges with the displacement value of 15 (any less and the displacement is barely visible, and any more just looks unnatural).
Could that be because of the textures being 2k instead of 4k?
Or that the heightmap greyscales are bad for displacement? I didn’t make them, but I tried playing around with the greyscale tones which resulted in very edgy walls displacing, instead of the pebbles popping out.
It could also be because of the landscapes’ resolution, what do you think? Here’s some pictures to demonstrate:
Erosion/dirt showing weird displacement:
Landscape resolution. The Cliffs look decent now
Heightmap greyscale of the erosion/dirt:
Actual dirt texture with pebbles:
Hmmm… can’t get the images to work. Getting errors when uploading them on Microsoft Edge, while Chrome doesn’t even show how to upload images.