This might work in theory on the initial heat up, except it will never be that precise due to having to still turn the heater, inevitable variable flame strength, and the difficulty of keeping the glass in neat straight rotation and even distance from the flame at all times.In the dab community, the technique for reliable hits is using a simple timer. Since you aren't really doing cool downs with this, just timing the heat-up might be fairly consistent for you.
And when dabbing it's common to hold your finger over the nail as an auxiliary temperature check, so gauging the radiant heat is a great idea at getting a second temp check.
However, for re-heats it would be much more of a guessing game I think. I may ask the temp chart experts for possible options to measure the temp of hot glass. If that could be done somehow, that should be enough surely for some sort of consitency or useful indication.