Yes it would be possible to do that for certification but very expensive to do that for recurring checks once certified. No one is going to spend thousands of dollars to have maintenance go to max altitude to check one light to see if it comes on at an extreme temp especially if you have to cold soak for hours in the right conditions to make it happen. Most polar flights the light doesn't come on. On this day several flights had it happen and descended to FL250 to get it out. If they had a ground check to calibrate I would be interested in how they would do it, sensor being in the fuel tank submerged with fuel and all. It seems they could check it easily now since they could just cut into the tank and test it in a controlled temperature box and see if it was accurate.