My man, I feel your pain - but no in the Superb 😜
I am around your weight and size, with long legs. Is not always easy to fit in many cars.
The problem you describe is typical in between 'normal' and 'sport' seats for most manufacturers, especially ze Germans.
I have driven extensively in my previous cars (Audi A6s), both in the 'normal' seat and the 'sportline' Recaro seats (yes, they still were Recaro's!).
The bolsting and support of the sport seat is much better for track/spirited driving, but not much more than that .... and after a while it really becomes numbing.
So probably there is not really a problem with the car in itself, it is just you that is not compatible with its seating position, thing that, unfortunately, comes to light after a longer drive.
When came time to choose the Superb, I did not even looked at the Sportline, also because of the seats.
Unfortunately, in recent years there has been a plethora of "sport editions" from most manufacturers, with a proliferation of s-lines, r-lines, sport-lines, black-lines, and who knows what else, puttting in second aspect the real comfort and instead putting oversize rims, harder suspensions, bolstered seats, questionable trim (black plastic and fake carbon galore!) .... to each its own, but this alienates a part of the market imo.