That's great that he started eating.
I second the advise that you got earlier about his cage. It's really too big for him.
I'm also worried about your watering system, I don't know what kind of setup you're using. You have so few leaves in your setup, and your setup is so large, I would worry that your little guy is able to readily find his water. Mistings are great, but he needs a regular drip going at least twice a day, and the drip should last for at least 20 minutes to an hour.
My initial thinking is that his appetite was low because of dehydration. Work on keeping him hydrated and his appetite should return.
I'd stick with fruit flies, pinhead crickets, and houseflies at his age. You seem to be doing good with feeders, small superworms should be fine, just no mealworms.