Love this mod. I think it would be fun to increase the difficulty by making cliffs spawn random ore underneath them when destroyed and the same for landfill when placed

Cliffs not having ore generate inside of them is a design choice. They look extra janky otherwise. I could make them spawn ore on destruction but that's a bit of effort. The landfill idea sounds interesting, but landfill is kinda meant to be a stone sink. There's a lot of settings to control how dense the ore is, availability of water, etc.