CoolProgrammer

Im attempting to introduce a custom world-gen json folder enabling structures such as mineshafts and ruined portals to keep generating within a sapling superflat in a 1.16.5+ server. But it's coming up fruitless. Importing the world with its json export from singleplayer saves leads to the server becoming unusable until the world is deleted, and using an edited export in place of it seems to not work so far. Do I have to put a certain json in a certain minehut folder, alter the files location within the world directly, or even simply upload it in a different order?