I had no idea that Jumpstarts have a tendency to fail within 2-4 yearsGotta look into that now, thanks for the heads up. One of my biggest nightmares as a snake owner is having a thermostat gone rogue. I'm planning to upgrade my BP's enclosure in a year so maybe I'd better get new thermostats at that time as well.
For equipment it sounds like you've got all the essentials! Great that you're recording temps too, you sound very meticulous about your BP care and it's really nice to see that. I think your BP is in good hands
The CHE set up you have looks great! Your probe positioning looks fine to me. Having two independent ambient temperature thermometers, one each on the warm and cool ends, is definitely a good idea, especially as you're still stabilizing temps in the enclosure.
I don't know how accurate Century Thermostats are unfortunately, the best you can do is try to compare its measurements with that of other thermometers and your temperature gun.
79-82F is an excellent range for ambient temperatures throughout the enclosure and surface temps on the cool side. I actually don't think you should go any higher than that for ambient temperature as that would be uncomfortably warm for the snake. I believe you said you have a UTH on the warm side too, right? As long as the UTH is under the warm hide and heating the surface of the bottom of the enclosure to around 86-90F, then you don't need to increase the warm side temperatures above where they are already at with the CHE.