I just want to add that in my experience, humidity is not something you need to think about, ever, when breeding dubias. I never mist, I don't have a water bowl, I don't use water crystals. The only source of water I have is the cucumber pieces that I put in there once a week. That's generally enough water for the colony. Of course, you need to adjust how much cucumber according to the population.
Also, the lid I use is basically a screen mesh, so it does not contain any humidity at all, that somehow got in there in the first place.