CathInfo.com

Yet, due to those Masses being offered publicly, the faithful who attend have a right to know if the priest who is offering on their behalf IS offering "una cuм" with Prevost, and the local Novus Ordo bishop or not.

Not that I am arguing they have right to hear the Canon spoke in in a loud voice!

Only if you're dogmatic about the matter one way or the other.  If you're not dogmatic, and I'm not ... I don't think there's any reason or right to know, ESPECIALLY when it means absolutely nothing when an SSPX priest SAYS it, since they're not in union with any bishop or with Prevost, not in any real sense, other than by paying lip service to them.  It's especially laughable when they put someone like Martin in there when Martin hates them and has tried to shut down everything they stand for.  You're kidding, right?  You can't be in communion with someone who doesn't hold communion with you.  It's a two-way street.

So the "faithful" who attend can also pretend they're really in union with Prevost and Martin when they're actually not?  To me, worse than simple material error in inserting the name would be that it basically is a LIE in the middle of the most sacred prayer in existence.

If I were a priest, I might say "una cuм famulo tuo papa nostro" but omit the name, since to positively assert that Bergoglio and Prevost are to be numbered among those "orthodox cultivators of the Catholic and Apostolic faith" ... well, that's just a blatant lie and does not belong in the Canon for that reason, whether or not you think they're Popes, since they're most certainly not orthodox cultivators of the Apostolic faith.  In fact, being "Traditionalist", the whole point is that you do NOT consider them to be orthodox cultivators of the Apostolic (aka Traditional) faith, right?  It's just a stupid lie that I could never say with a straight face, not in the middle of the most sacred prayer every offered to God, whether or not I believe they're popes or not popes.