Can you establish a registration-for-prorogation requirement in copyright?
I would not think Berne plus TRIPs would be violated. Once the minimum term provided by such Agreements are complied with, any further extensions would arguably be free from their scope. See Article 5, paragraph (1) of Berne (...as well as the rights specially granted by this Convention). Convention plus TRIPs specially grants to all a term, with all the trimmings, including the no-formality rule. Beyond that, national legislation is on a freehold.
Therefore, the registration-for-extension (in excess of TRIPs minimum term) requirement would not be violative. On the other hand, the first registration is already infringing....except if we accept the convenient but dubious interpretation that U.S. Laws can impose locally the registration that would be void under Berne.