"Beyond the mountains" would be the transliteration. European description. over the Alps in to Italy.
The Pope when teaching to the whole church in matters of faith and morals is infallibly safe to follow. It might not be infallible in the strictest sense of the word because it's not ex cathedra, but his teachings and commands to the whole church can NOT contain pernicious errors. The Pope can say that the moon is made out of cheese, but he can't teach that public adulterers can receive Holy Communion (Franky!).
This isn't my opinion. This is the teaching of the Church's theologians on the Magisterium and Infallibility.
I am pretty sure that sedes do not believe in the dogma of papal infallibility at all.
Let's put it like this, if you actually believe in the dogma - which we are all bound to believe, then it is through faith in the dogma that you know with dogmatic certainty whenever the pope speaks error to the whole Church, what he said was not divinely protected.
Trying to convince people that everything he teaches to the whole church is infallibly safe, is Novus Ordo thinking, which, whoever *really* believes this should certainly be Novus Ordo themselves.
The only alternatives are that they either do not believe the dogma, which is the actual reason for sedeism, or they believe the dogma on papal infallibility is in error.