Again, I am not arguing for the charism of infallibility as a “larger category”.
But it is. By definition. Otherwise it’s just “the Holy Spirit didn’t let the Church mess up on this particular occasion,” which is not controversial.
Perhaps we mean different things by “the charism of infallibility.” But I don’t think so, because presumably you want to argue that the Church can reliably be expected to possess this charism when needed.
If the charism is simply the Holy Spirit guiding the Church, with no guarantee that it will ever happen again, then I don’t think it’s controversial.
I am merely asserting that if you believe that the Church got it right (or, if you wish, did not get it wrong) regarding the canon of the NT, then you, necessarily, believe that the Church was given the charism of infallibility. At least as it applies to the canon of the NT. Over and over and over again.
No, not really “over and over and over again,” because there were all kinds of canonical lists produced by the early Church which did not correspond to our canon today. Clearly large parts of the early Church didn’t get it right. Eventually, according to both Protestants and Catholics, the early Church got the NT right, at least.
I still don’t see how a charism of infallibility is necessarily implied, unless you simply mean that the Holy Spirit guided the Church on this particular occasion.
I think perhaps a better way to approach this is: on what basis are we confident that the Church got it right?
Catholics are confident because they (we?

) believe in the charism of infallibility.
Protestants give other reasons for their confidence.
I don’t find that those reasons justify the level of confidence Protestants have. But the fact is that they do give other reasons. There’s no need to argue that they really must believe in the charism of infallibility. They don’t. That’s their problem.
If, for instance, modern scholarship confirmed beyond reasonable doubt that all the books of the canonical NT were really written by apostles and were historically accurate, then the Protestant position would make sense.
So often on this forum, my disagreement with common Catholic arguments is not with the final conclusion but with the use of a priori rather than a posteriori arguments.
Protestantism isn’t incoherent as a matter of principle. The evidence just doesn’t support it.
If Scripture really testified about itself in the way many Protestants try to claim it does; if rigorous modern scholarship had confirmed the accuracy of the Bible in the way that some Protestant apologists (and Catholics too) try to claim it does; if Protestants had for the most part been able to form an agreement on doctrine on the basis of Scripture alone; if the Protestant Reformers’ interpretations of the Church Fathers had been sound and honest; and above all, if the Catholic Church had either faded away or become more and more obviously corrupt and apostate, rather than emerging as the clearest upholder of “mere Christianity” in the modern world; if all of these things, or even most of them, had happened, then Protestantism would have a good case to make for itself. Since none of them have, it doesn’t.
Edwin