I have a hygrometer too and that is showing about 50-60 on each side consistently so I am not worried about the humidity that seems fine. I have seen it go up or drop a little but it always corrects itself so that seems good.
Well the probe for the UTH thermometer is under the substrate so that's what is set at 108 right now so the glass floor is probably about that temp, but I only raised it that high to make the tank heat up which is still not working so I can lower that temp if I need to supplement it with a bigger lamp....
As for measuring the temp of the actual floor of the substrate, I don't know how I can accurately do that...