how well do the cvt transmission hold up and what are the signs that its starting to die
If the CVT has not had its fluid changed regularly… 60k miles to as soon as every 30K miles they can die as early as 80K miles or less… So about the average number of miles on a 2012 car… you didn’t tell us the mileage.
Symptoms vary but if the car isn’t shifting correctly and there is no check engine light, it is probably the transmission.
The CVT used in Subaru’s from 2012 and newer is a newer design that holds up much better than earlier generations. It is expected to last 300k or more miles under normal driving with no maintenance requirements. If you regularly pull a trailer, then it does need ATF changes every 25k miles.
I checked my ATF at 60k (14 Legacy) and it showed no deterioration at all. I have a 122k one it now and have no plans to mess with it or check it again.
Because it does not have shift points like a geared transmission, you really can’t tell if it is slipping or just gearing down. Both feel the same. I’d say if you notice a significant drop in performance or fuel economy, that would be one thing to look at. OBDII has a provision to check input shaft speed to output shaft of the transmission to see if it is outside the parameters for the given condition and turn on the check engine light if out of limits.