Firstly, if you don't understand text goto 15:40 in this video.
terraforms seem to just fix the ground.. this means the mushroom terraformer plants mushrooms, makes them superbig, turns the top of mushrooms into mycelium, and can occasionally make bigger mushrooms on the top of that.
I suggest block blasklists for terraformers so they aren't doomed to repeat this,
You could also make it so players can blacklist blocks themselves, and turn certian blacklisted items on and off for certain terraformers, via a GUI!
Eh whatever floats your boat, i like the first option.