I can't change the Aether's biomes... help!

I've tried changing the data/aether/dimension/the_aether.json, data/aether/dimension_type/the_aether.json and even the data/aether/tags/worldgen/biome/is_aether.json files... None of these allow me to alter the biomes present in the mod, and I was wondering if maybe I am doing something wrong?