As long as the humidity is around 45-50 in the whole terrarium that should be perfectly fine. Just raise it when your BP is in shed.
Yes, if you want to raise humidity, just dampen the substrate a bit and mix it around. Then let the humidity stabilize. If you need to raise it further, repeat the process.
What substrate are you using?
Sent from my SAMSUNG-SM-G920A using Tapatalk