My pleasure ;)
Maybe "reverse growing" would help? Or...
Paramat told me that he proposed a change to the engine that makes "is_ground_content" be responsible to tell mapgen that generating caves is NOT "ok". So nodes with "is_ground_content=true" don't get replaced with air.
Maybe water would respect that too?
Also, I've just noticed a weird bug:
screenshot_4017236543.png
It's decorations that spawn on
anything (cobblestone mese lamps in this particular case).
Snow is also affected.
Edit: Oh, there's more :)
TenPlus1, could you change default:stone to default:desert_stone in fiery biomes craters? I think that reddish color of the latter suits here more. Or, if you don't want, then can you tell me how to edit schematics?
Edit1: Nevermind, GHex + some basic knowledge helped me to do it w/o worldedit :)