Ground cover recovery help

Hi, I was editing my map and saved everything and when I opened the game again I noticed that the ground cover is gone as seen in the photo. Is there a way to recover it ? I tried adding new ground cover but it's just boxes of No Material here and there.


--- Post updated ---
I fixed it by copying items.level.json from the original Jungle Rock folder. My ocean and river preferences were gone but I don't mind editing them again, at least I know how to. I am open to suggestions on how to improve the grass now.

Also I would like to add a rainbow to my map that looks the same from all angles like the grass. Can someone show me how to do that ?