Well, when I had one front break on wife's late 2002 Polo at about 4 years old, the replacement I bought was labelled up as being made in CZ - now that follows as the "lead" marque for this platform at that time was Skoda. It could be if the new Fabia was launched before the new Polo or
Ibiza, then Skoda is still the "lead" marque for this revised platform, so once again all the running gear will be CZ sourced where possible to save money. I have noticed that the front spring on daughter's late 2009
Ibiza is a bit curdy near the bottom. Bad road surface will exacibate this issue, poor quality material including coating will be the primary issue I'd expect. The issue of "these cars being built for European mainland use" does not come into it, Seat UK should have made sure that all UK sold cars are correctly protected for our roads and weather. Remember it is VAG we are talking about here, not Seat of old who did not even bother to engineer in door safety latches - when even Lada had probably included them!
My advice to anyone replacing broken VAG car springs is, if the car is beyond warranty period, only buy springs made by and branded by spring manufacturers - not from car manufacturer's parts place. Ie aim to get Swedish made springs and not CZ made springs.