I would like to disable the crystal forest biome from spawning as it is a bit overwhelming. So i see this config option, and set "Crystal Forest"=false, but that was not the case. The biome still would spawn in my world...so I assume there is must be a bug with the config.

Also, I would like to add, an option to disable the crystal tools (from the registry, of course) would be a nice addition with this as I dont want to make them an option in my modpack to use as tools.

You wouldn't happen to have another mod that's controlling biome placement, would you? If the config is false, the Crystal Forest is never registered to the Biome Manager, and will not spawn in the world. However, it is still registered to the forge registry (this will not change), so another mod may be picking up on it. You would have to disable it on that mod's end.

You mean like world generation? I have BoP if that helps, but i don't really understand what you mean about "Biome placement". Is it an internal thing, like when a mod needs to use biome ids for item registration, like evilcraft/exutils2's biome manipulation/terraforming?

A mod such as Geographicraft is used to control biome placement. Usually it relies on the Biome Manager to select valid biomes, but I'm unsure if the BoP worldtype respects the manager or uses the registry.

Bleh. I'll just disable it in the registry. I was trying to avoid that because it will cause the "x is missing from the registry" screen when you open an old world, but if mod worldtypes aren't respecting the biome manager, not much I can do.