Yes, it IS a design fault, joint between metal part and plastic part of fixed frame.
No liabiility accepted by Skoda at 5years /65k miles. - poor responsibility since it is such a common, well-documented serious fault on sunroof Yetis.
Not difficult to take headlining right down and expose leak paths on headlining/
Disconnected drain pipes was one fault and easily fixed.
Capillary leak did not respond to Captain Tolley's sealant / hypodermic needle applicator.
Other leak paths at rounded leading edge corner of rubber seal needed sealant to hold down and to gap-fill the (tubular) rubber seal.
Gaffer tape paint-to-glass looked unsightly and didn't stop the leak at all (3 gallons water from O/S front and rear footwell)
Decided other temp fixes would still impact any resale value more than a Skoda Dealer fix guaranteed 2 years Parts and Labour at £2300. (Ouch!) (Plymouth, UK)
The sliding roof fixed frame is extremely fragile - part price = £1400 - so asking an independent garage to do it was much too risky
Memo to self - remember to flog the car before 2 years is up - well before!
Yeti Design??? not impressed at all - too many ill-conceived and unnecessarily shoddy design features, long term reliability not fantastic.