Dreamland is a mod for Forge that aims to add unique fantasy-inspired biomes to the Overworld along with new mobs, effects, and more! The mod was developed with the help of Terrablender.
The mod provides config files for changing values for several features. Data files are available for world gen features such as biomes and features, just like vanilla Minecraft. To tweak world gen for the mod, a datapack can be created. For reference, check the data folder.
When creating a new issue please ensure that the problem is caused by this mod specificly. Include the version for the mod, dependencies, and forge. Including a crash log or log significantly helps with tracking down issues.
Download: https://www.curseforge.com/minecraft/mc-mods/dreamland-biomes