Well, that's what I was told by service as the PCS is the Power Conversion System for AC to DC charging. Supercharging is direct DC charging so the PCS is not used. HOWEVER, I suppose if it goes out in some fantastic way, it might damage something else? I don't have all the answers-just trying...
If you've had a "reduced charging event" that is a sign of pending failure. I'm guessing your home L2 charger charges at MORE than 24 Amps so BOTH PCS converters are in use. One of them starting to fail would REDUCE your HOME charging RATE to only 24 Amps and set off that error/warning.