How to control a mob's spawn biomes via a config

So I have a mod that adds a new mob to the game that currently spawns in a couple biomes naturally. I moved to manual coding and learned how to create a config file, and I currently have that working properly to control the spawn rates of the mob. However I'm not sure how to control the spawn biomes like this. It seems like MCreator handles mob spawning a little differently than normal, and so every forge modding tutorial on YouTube doesn't seem to directly apply.

I see that in the entity.java file it has a section about spawn biomes right at the top, but since I'm new to coding I'm not sure exactly how this works, and how I can insert a series of values from a config into that biome section.

Thanks!