Need a way to change what dimensions techguns mobs spawn in, as they spawn in untold numbers in certain dimensions that are permanently dark.

Until the update comes out (eventually) I recommend the mod 'In Control', it works well with every mob, mod, and also every dimension, as well as even more parameters.
https://www.mcjty.eu/docs/mods/control-mods/control-mods-legacy

I Implemented a biome blacklist already, will be in next release.

The config file contains a String array where registry names of biomes can be put and for biomes entered there techguns mobs will not be registered as spawn.

This is how it will look like:

    # Biome Registry names (e.g: minecraft:mushroom_island) that are excluded from Techguns monster spawning [default: [Ljava.lang.String;@74786396]
    S:BiomeBlacklist <
        minecraft:mesa
        modid:modded_biome_name
     >