The current version of the mod uses the harcoded BiomeProviderSingle

The mod should ideally have configurable list of biomes so that other mods can hook onto the generation of the Aether dimension, thus, mods like BiomeTweaker could interact with it. This is, above all, a technical request for modpack makers who want to flesh out the dimension.

P.S. pretty sure this is not relevant for gilded games at this point, but I would be truly awesome if this feature could make it to 1.12 too.

Should probably move this to the The-Aether-Archived repo since that's the 1.12 one.

Well, although I'll do that too, this could still be advantageous moving forward. Let me know if this is relevant for versions above 1.16; if not and the methods are all different, then you can just close this issue

This could still be relevant so I will rename it to be more accurate to its relevancy. I imagine it'd likely have to be done differently in 1.16+ due to world gen changes but as I'm not one of the 1.16 devs I'm not sure of the specific differences.

Given the fact we're in 1.16 land, you could easily just add biomes to the Aether using a datapack!

You could overwrite the aether.json dimension file (which defines how the dimension generates and what biomes appear) and change the aether's biome provider. At least I think. I don't know entirely!