Darker Depths is a cool cave biome mod that I feel could fit into the pack pretty nicely. It adds many new building blocks + new ore gen in its biomes. Combining this with the other cave mods in the pack could make the underground very interesting to explore and mine in. https://www.curseforge.com/minecraft/mc-mods/darker-depths

I totally agree with this, if darker depths were added and maybe cockroaches and/or cave centipedes were enabled caves would have significantly more aesthetics and functionality.

Dupe of a closed issue by me. Even closed Caves and Cliffs Backport by the same dev, I think he just likes Quark cave biomes.