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Well, those are interesting case studies, Clemens.

Now, I am in fact a dogmatic facter, in the sense that it's logically (theologically) certain that the legitimacy of a pope must be dogmatically certain, or else nothing they define as dogma can be dogmatically certain.

What's at issue is what criterion determines whether the legitimacy of any given pope is dogmatic fact.  It has always been held to be universal peaceful acceptance, but I will read up on and consider the case studies you posted.

But even while upholding universal peaceful acceptance, I do not consider rejecting Bergoglio to be heresy, since he decidedly lacks such universal peaceful acceptance by Catholics.

Perhaps the answer is that John of St. Thomas did not correctly think through the quoad se vs. quoad nos distinction.

If a Pope were elected and universally accepted, then he's Pope by dogmatic fact.  When a subsequent man comes along, deposes him, puts him in jail, assumes the See with new "universal acceptance", the universal acceptance means nothing, for the quoad nos cannot override the quoad se.  No subsequent universal acceptance of another man can cause the deposition of the original pope, for that would be a flavor of Conciliarism, where the Church can effectively depose popes.