I dont know if this might be planned, or already in game, but here goes anyway.
I think high level terraformers should be able to manually type in the desired height gain or how far down it should dig when terraforming.
The current system makes me pull my hair out when trying to level something flat. (I know about the "it only levels according to the tiles left and right of you)
Its just horrible, and really, a master terraformer SHOULD be able to have more control than the average terraformer. Maybe the average ones should be able to type in a value, but with a risc of it going 40% off or something.