You must have missed all the previous citations. Councils have Ecuмenical status if and only when they're approved by the pope. No legitimate pope = no Ecuмenical Council.
As for the gap in time, the Magisterium can go many years without defining anything new ... without it thereby ceasing to be the rule of faith.
The pope was legitimate when he convened the Council, you cannot even think otherwise much less prove it - particularly if all councils are automatically infallible - and there is no mistaking here, V2 was a real, genuine and authentic Council. As a real council, both the pope and the council were infallible. This is the common thinking and a major reason that +50 years later, we are still in this crisis.
As for not defining anything, that has not been the issue because V2 never defined anything, yet you and the others say "An ecuмenical Council is an Act of the Magisterium" and ecuмenical councils are infallible because they are "an act of the Magisterium."
Now you gratuitously add "No legitimate pope = no Ecuмenical Council" into the mix, though you as much admit that nothing that came from V2 was binding on anyone anyway - so why did basically the whole Catholic world submit?
Because they believed they had to because that is what they were taught. Because they believed that all councils are automatically infallible, that V2, being a council was by default infallible, that the pope is infallible when he isn't - and if that's not enough, they also believe that whatever the bishops and pope teach in unison is automatically infallible. Whoever believes all or even any part of this errs in *not* submitting - period.