I have a 2012 Superb estate and i have exactly the same issue. In fact it became so bad that the passenger side footwell was waterlogged and as the floor is double skinned, the void filled up too. The first related issue was that i would go tot he car in the morning and the battery would be dead flat - not enough juice to unlock the car so, i had to access manually. Next thing I noticed was, that the passenger heated seat would be on when the switch was off and later, a smell of burning cable insulation from the connectors for the seat adjusters. I wet-vacced well over 5 litres of water out of the carpets and they're still wet - because of the water in the void. I had a new screen fitted - damaged so unrelated - I thought the leak may have been from the corner of the screen but the chap doing the job said he'd seen loads of issues like mine on these and other makes and, it was most likely the drain pipe. Here's the link that I've sent my mechanic - it's for a Yeti but i'm told on this site that it's good enough to do the job.
https://www.briskoda.net/forums/topic/294146-leaking-panoramic-sunroof-have-a-look-here/?tab=comments#comment-3494177