[guan]

A clause like the one you describe is fairly common: it just says that if you violate the .it terms and conditions, they can sue you in Italian court.

I would be more worried if there was language indicating that you live in Italy or have an Italian presence. For example, to register a .us domain name, you need to be either a US person or have a substantial connection with the United States. It's still a stretch to imagine that it would have tax consequences, but much more likely than a venue clause in the domain name contract.