As you said, mold is just part of the decomposition process. IMNSHO, it IS possible to have too much mold, but that condition usually corrects itself eventually.

BTW, from your description, I would guess that you are putting way too much dirt in your bin. You don't need any at all.

Yes you can use coffee grounds. But I have visions of a new bin with a pots worth of bins added daily. If so, maybe back off on the coffee grounds, shreded paper and dirt. Add corrigated cardboard, coffee tray, and kitchen vegetable and fruit trimmings. These are compost worms, if you ordered compost worm. Not earthworms. Compost worms live in compost above the ground. Earthworms live in the soil. Learning Process.

My worms love mold!

Be sure to keep some bedding available for them. Mold is good.

Don't put pine needles in your compost bins.

>>Don't put pine needles in your compost bins.Pine needles aren't forbidden, they won't hurt the worms, they just take 3+ years to break down, and their little sharp, pointy ends keep poking you when you need to go through your bins by hand, making them very annoying to have in the bins.

Not only is mold ok, it's essential for the worms!

Here is a link that might be useful: Mold and composting worms

Humor. Points for that. Dirt no. How about rock dust? A product with biochar, mycelium and rock dust would be the cats pajamas.