I can see only two possibilities if the teachings of Vatican 2 are part of the Universal Ordinary (or Extraordinary) Magisterium):
1. The Church was wrong before Vatican 2.
2. The Church is wrong now.
Or you're missing some distinction that would make them reconcilable. And THIS is the problem I have with SVism. You act as if it's certain with the certainty of faith that these two are in contradiction, but in point of fact you're using your private judgment to determine this.
Yes, it sure looks like it to me too, that these are in contradiction. But I also realize that my private judgment cannot resolve this matter with the requisite certainty. In fact, there's ZERO contradiction between these if you hold the same ecclesiology as most Traditional Catholics.
That's why I'm on the fence. If someone could convince me that my own ecclesiology is wrong and that of the Cushingites is right, then I immediately drop all opposition to Vatican II.
I agree with your point that the main errors of Vatican II are in regard to ecclesiology and soteriology and that many Traditionalists unfortunately hold them too, nevertheless I think that the "Cushingite" ecclesiology is not the only problem of Vatican II and even adopting it is not enough to "drop all opposition to Vatican II". There are still scandalous statements in
Nostra Aetate regarding false religions - Traditionalists, and even many Novus Ordites who believe in salvation through invincible ignorance insist that the infidels are saved "in their religion", but not "through their religion" (as Archbishop Lefebvre unfortunately taught), while Vatican II teaches that false religions themselves have positive qualities and bring their adherents closer to God. This gave rise to heresies expressed by V2 Popes and members of the Conciliar Church that the Old Covenant is still valid and Jєωs can be saved by it, that Muslims can be saved through observing Islam, that God manifests himself to people through false religions (explicitly taught by John Paul II in
Redemptoris Misso) etc. On the other hand, Traditionalists who unfortunately hold to salvation through invincible ignorance nevertheless believe that false religions are an abomination for God and people are not saved through them. So the error of Vatican II is much deeper than that of "Cushingite" Traditionalists.
In short:
1. Vatican II and Conciliar Church: people are saved in non-Catholic Churches/non-Christian religions and these Churches/religions are positive means of their salvation.
2. "Cushingite" Traditionalists: false religions are an abomination and the non-Catholic Churches are heretical, but people in them can be saved in spite of that.
Even though both positions are erroneous, the difference is crucial - Vatican II position taken to its logical conclusion leads to the endorsement of false religions (for which the V2 Popes are indeed notorious) and the ecuмenical apostasy we see right now, while "Cushingite" Traditionalists' position does not.
Then we have Vatican II's admiration of man expressed especially in
Gaudium et Spes, which gave rise to humanism and anthropocentrism we are observing currently in the Conciliar Church.
Finally, the problem with Vatican II is not only its explicit teachings, but also employed modernist hermeneutics which became rampant after the Council and which notoriously mark the later Papal docuмents and actions of the Conciliar hierarchy.