There's no doubt. They differ only on their acceptance of Vatican I and therefore do believe that there are in some (according to them) very limited circuмstances, truths which are guaranteed a priori to be consistent with Tradition.
But the tenets of R&R are nearly verbatim the Old Catholic talking points. Had they been around at the time of VI, they could just as easily have rejected the dogmatic definition of papal infallibility.
Papal infallibility is in fact a very curious dogma. It's truth depends on whether it's true. In other words, if the Pope teaches infallibly, then infallibility must be true. But if it's not true, then it's possible that the definition of infallibility was mistaken. It's a bit of a conundrum.
So what guarantees it to be true? It's actually the BROADER infallibility of the Church. God would never allows His One True Church to corrupt the faith this way. And yet R&R reject that principle, and do hold that it's possible for the faith to be corrupted. Consequently, for them, the dogmatic definition of infallibility is build on a foundation of straw.
Doesn’t this also apply to Sedes tho? If Sedes were around at the time of V1 they could just accuse pius IX of some heresy or another and conclude that he isn’t actually pope.
it does seem to me that the logical conclusion of this reasoning is that V2 can’t be erroneous because God wouldn’t allow the visible church to get wrong who the pope/councils are