In my experience, a fridge does not provide a steady temperature--at all. There are hot spots and cold spots. There are spots that will freeze, too--especially at the back of my fridges this is common. That said, I haven't actually tried overwintering Stewartia spp. cuttings in the fridge. I discovered this stuff stratifying seeds in dedicated refrigerators, mini-fridges, and the regular kitchen fridge.

What is the full set of details of what you have done with your cuttings up to this point? Because typically with deciduous cuttings - of less than very easy types that cannot be done from fall or winter hardwood cuttings - you have to take them really early (like in May) and get them rooted (under mist) in time for them to flush a top growth, set winter stem buds before the first fall. Or they will not grow away again the following year.

I haven’t taken any cuttings this year. I plan on doing it next year in June or July as semiripe cuttings and I plan on exposing them to as much light as possible once rooted to give them a flush before entering dormancy. Apparently that helps with winter survival. But with the fridge, I guess if I buy one of those small ones and keep that in a separate room I don’t ever have to open it since there won’t be any food in it so hopefully that may help with temperature fluctuation? I will try to determine the temps for each spot in the fridge with a thermometer. Not sure this is gonna work but I want to try cuttings if my seeds fail

They make very cheap remote thermometers with multiple sensors now. You can buy one thermometer and connect as many as 3 remote sensors. I got mine on Amazon... I would put stuff in the fridge. At least, I have been told by people who should know better than I, the more stuff there is in the fridge, the stabler the temperature will remain in any given spot.