A single-setpiece level

[skittles sour]

I'm trying to make a whole worldgen level out of the final chapter of adventure mode, and I'm trying to adapt Serp's adventure mode mod. I've created a level, a taskset, a task, and room and a background room, and adding the setpiece as a required setpiece in the taskset and in the task. Right now the only correct things the worldgen is getting are the size of the world and roughly the shape of the island - I suppose the worldgen must have taken the setpiece and emptied it out for something. My modwordgenmain currently looks like this https://pastebin.com/AjcJyha4. Any help would be much appreciated!