Imagine that the much "daily-er" Pilot Super Sport got a terrible score in the wet in recent EVO's performance tyre test, so I can only imagine the PSC2 being even worse under wet and cold weather. Will be fitting Alpine A4 to mine.
Michelin PSS scored 96.6 out of 100 for wet performance on a track in that Evo test - hardly a "terrible" score. That score was gained on a Focus ST and not a performance Golf, being flung around the track. Off the track performance, you'll have to go with views of users, and after swapping my dire factory fit Bridgestone RE050A for PSS, my R was transformed, performing very well last Winter after that January change.
Even in the wettest of conditions, they haven't skipped a beat - even driving the car hard to 70mph from a standstill up a long and steep sliproad from Scotswood Road in Newcastle up to the A1 Northbound. Pretty much all of the tyres in that test would do you fine driving as hard as you can lawfully on the road.
I'd have no qualms in recommending them on a Golf that is used on the road. With the last few winters being very mild, even up in the North East, I haven't felt the need to invest in Winter tyres for the 3 days it dipped below zero on my 7am commute last Winter - PSS were good enough for me. Semi-slick tyres might be another matter though!
The 96.6 of the wet lap is just a number which seems close to 100. But it does not say much really unless you put it into context, meaning the actual time scored and where exactly it was placed against its competitors. So that will be 72.11", a 2.5" slower than the 1st placed Pirelli and second worst overall (more important). Moreover in the wet, the MPSS scored:
77.8 on the wet handling feel (2nd worst)
93.3 on wet braking (3rd worst)
97.7 on the wet steerind pad (3rd worst)
Now you're free to interpret those number as you wish, but "excelling in the wet" would seem a vast over-statement in my eyes.
As for which car was used, a Focus ST is far more relevant to the FWD Clubsport's behaviour, (problematic traction under full throttle on the wet) than your AWD R that you are using as a reference. I was actually glad to see the review was based on such a car and not on a AWD and thus flattering lesser tyres.
In any case the question here is the PSC2 and for that, there are already reviews from Cupra owners that run it as part of the Sub8 pack. It's fair to say much prudence is needed in cold conditions. When I was about to order the Cupra and deciding whether to get the PSC2 or not I had read almost every review in cupra.net and decided a less hardcore tyre would be more sensible for a daily car based on what people were reporting.