As far as the SV vs. R&R issue, this constant arguing about Bellarmine vs Cajetan, and the strict limits of infallibility per Vatican I are to miss the forest for the trees. These two arguments have long been a distraction.
Catholics can hold either opinion about the heretical Pope, as neither have been condemned. While R&R minimize infallibility to the point where the entire Magisterium can become corrupt with the exception of a small handful of dogmatic definitions where the Pope practically has to say "I infallibly declare ...", SVs often overreact by exaggerating the scope of "infallibility in the strict sense" (as per Msgr. Fenton)
But we're not talking here about some papal teaching in an Encyclical. We could argue about infallibility there. We're talking about creating an institution that lacks the Marks or Notes of the Catholic Church. There's been a substantial alteration of the Church, or, rather, a replacement of the True Church by a false one that is now eclipsing it ... as the Catholic Church cannot be altered.
And we're not talking about a Pope spouting hersesies during his airplane press conferences. We could argue Bellarmine vs. Cajetan / John of St. Thomas here, and would rightly say that it's not our problem and that the Cardinals and bishops of the Church should deal with him. We're talking about their teaching heresy and grave error to the Universal Church purportedly from the Chair of Peter.
We're looking at an institution that has a thoroughly corrupted and Modernist "Magisterium", not only an Ecuмenical Council but 60+ years of not only unreliable and worthless but postively harmful "Magisterium," an institution that has adopted a form of public worship that is offensive to God and harmful to souls, an institution that has corrupted and relativized the moral law, and one that has polluted the catalog of saints by including the likes of Roncalli, Montini, and Wojtyla, the greatest destroyers of Catholicism in all history. To assert that this substantial alteration and corruption of the Catholic Church can proceed from legitimate Catholic authority freely exercised is to reject the indefectibility and overall infallibility of the entire Church, and renders the Catholic Church as a "rock" and a reliable source of truth (even if not infallible in every detail) not only meaningless but even erroneous. It renders the Church Herself meaningless, and even harmful. This is simply not Catholicism to assert this.
Outside of upholding the substantial indefectibility and overall infallibility / incorruptibility of the Church, Catholics can hold whatever opinions they like: papa haereticus ipso facto depositus (Bellarmine), or papa haereticus ab Ecclesia deponendus (Cajetan / John of St. Thomas), or could hold some hybrid opinion that nicely reconciles the two, such as sedeprivationism or sedeimpoundism (where these heretic popes have lost all authority but retain the office until legally declared deposed), or one could hold that Montini et al. were/are being blackmailed and not acting freely (which would render their official acts null and void), or even that Montini was drugged, or replaced by a double, or that Siri was the true pope until his death in 1989 but then afterwards Ratzinger and Bergoglio could not exercise papal Magisterium because they were not bishops (only bishops can be part of the teaching Church). Whatever one of these opinions one holds to are details, and not matters of faith, but we simply cannot throw the Holy Catholic Church, the One True Church of Christ, under the bus in order to salvage Jorge Bergoglio walking around in a white cassock. At that point, you might as well be an Old Catholic or Eastern Orthodox (if you aren't already, theologically speaking).