Mealworms are a great high-protein treat for quail, but are high in fat and should be given in limited quantities. The limit is like 6-10 mealworms per bird per day. Also be cautious if you feed live mealworms, because they can survive quail stomach acid for a short amount of time and gnaw into the quail's stomach lining!! Better to chop their heads off before offering them to your birds, or you can order freeze-dried mealworms in bulk. Chickens will love them, too.
The best live food supplement, in my opinion, is feeder cockroaches. High protein, low fat, and they provide stimulation for the birds while mimicking wild feeding behavior. They're not common, though, so you'd have to order online and maintain your own colony and not everybody is cool with having cockroaches in their home, captive or no.
If you give cuttlebone, make sure it's the ground-up version and not just a whole cuttlebone, as i don't think the quail are strong enough to get what they need from a whole cuttlebone. Ground oyster shell from a feed store, offered in a separate dish, might be cheaper and easier for the quail to eat. They really go through that stuff!
Seeds are a great addition to your feed, but they will reduce the overall protein intake of your birds per day as they fill their crops with seed. You'll need to compensate by offering a higher-protein (26-28%) crumble. I use a wild quail and dove seed mix that i got at a pet store, but finch seed works well, too.
Order some gamebird crumble online or check out ingredients online and try mixing your own. It's a lot of work but if you have the time it's worth it to know exactly what your birds are eating. Consider that if you're raising these birds for meat, whatever they eat becomes what YOU eat!