Greetings,
Just as a point of reference, I have a 2020 Legacy Base 2.5NA. As you know the Legacy does NOT have the CVTF cooler installed unlike the Outback which does.
Here are my CVTF and Coolant temps driven on a sunny day last summer when I picked up my new car (2000 miles on it).
It was clear, sunny, dry day with the outside temp 93F and humidity was typically high for Texas.
Starting temps: CVTF: 91.4 F and Coolant: 91.4F
After 9 mi warmup at 45 mph: CVTF: 159.8F and Coolant: 194F
After 40 mi highway cruise at 65 mph (TWICE): CVTF: 199.4F and Coolant 190.4F
After 20 mi stop+go in traffic: CVTF: 201.2F and Coolant: 194F
All the driving was done in one outing. I did the 40 mi highway both with cruise on and the first 40 was done in manual 6th gear (~2600 rpm) then in "D" (~1800 rpm). Both times the temps were the same (only +- a few F).
At the end of all the testing the Oil temp was 206.6F
Hope this gives some insight on when to service the CVTF.