Alright, so I'm playing Minetest's version of skyblocks right? Well, I left a hole in my cobble generator by mistake, and so lava was leaking out. When I went to build my upside-down house, which I used water to get underneath. All that lava that was leaking from 800+ blocks in the air, eventually turned into cobble. Now it lags the local server.
How can I remove them w/o losing my progress??
I've tried WorldEdit, but because of the lag, it can't remove the nodes.
Edit: There is still lava and water flowing down even though there's not supposed to be any.

