Temperatures seem more than a bit high to me-- FDA recommendations [1] are that fridge temperatures should remain below 40°F (~4.5°C) for food safety (to inhibit bacterial growth). This fridge is never making it below 5°C, and (from the real-time data linked in the post) it's peaking uncomfortably close to room temperature-- I see one spike all the way up to 16.5°C, and it doesn't look like it recovers quickly at all.
@IBob on temp probe placement, I think I know why it was seeing such sharp swings when outside the water. I had the wire coming down along the inner fridge wall corner, touching it for a foot, and then the probe was pulled out an inch from the corner. So, it was both very close to the walls, and wire's contact would suck more heat away when the wall cooled down.
The spring thermometer I have mounted in there to measure the air temp now avoids this problem, and has been staying just above freezing during long compressor runs despite frost buildup on the walls
Another resource in this kind of measurement would be the mean kinetic temperature -- often it's not entirely useful knowing that the fridge is 15 C or whatever after you open the door and get something; you really want to have a reasonable measurement of how much the temperature of the contents changed in that time and in the time until the fridge interior returns to the set temperature average.
[1] https://www.fda.gov/Food/ResourcesForYou/Consumers/ucm253954...