Could you help me please, how create custom world generation atapi 8. Custom world should include custom biomes and buildings but if I use template for create world , I can use only default biomes
The issue with custom world generation is the implementation changes so often in minecraft that other aspects of the api are priorities over a custom world generator that can only be used for a single minecraft version.
So while you are on the right track in terms of world template. You would need to go into minecraft’s code to create your own world generator.
With that being said, if its a biome from a mod you want, then you can use that by getting it from the Registry