I saw a YouTube video of demonstration in teraforming in Minecraft utilizing their version of WordEdit to create a stone arch and a pool.
Then a horizontal cylinder of sand (like mauvebic's multinode mod) was positioned in the airspace above the stone arch and pool and was allowed to drop over the arch and pool. The vertical center of the sand cylinder created a taller stack of sand and the the edges of the cylinder produced shorter stacks.
Perhaps some combination of worldedit, moltinode and landup mods to create a map editor. Fly over an area, worldedit select the area, mulinode to select a round-toped cone, and landup to produce a mountain, foothill or hill. Use the process in reverse to create gullies, ravenes, and deep oceans and lakes.
Thanks for giving this some concideration.