This thread has moved away from the initial topic: the possibility of faithful disagreement on matters of discipline, and on rules and rulings under the temporal authority of the Church. So I will make a few closing remarks, and then close the thread. (Please do not reopen the same topics in a new thread.)
On the question of liturgical norms, there is a range of faithful opinions. A faithful Catholic can hold that everyone should adhere to the norms. A faithful Catholic can hold that relatively limited departures from the norms are permissible under the eternal moral law; it is not a sin, and so it may do more good than harm.
However, it would be a serious doctrinal error to treat any matter of discipline or prudential judgment as if it were a dogma (infallible doctrine). Dogmas requires the full assent of faith (theological assent). Non-infallible doctrines require only the religious submission of will and intellect (religious assent). Non-infallible teachings allow for the possibility of licit theological dissent, within certain limits, called the norms of licit dissent.
But matters of discipline and prudential judgment, even by the Pope about a grave matter such as war or the death penalty, are not teachings and do not require assent. A faithful Catholic can disagree with the Pope, or the local Bishop, or a Cardinal, or the local Bishops' Conference. A faithful Catholic can also disagree with a liturgical norm, or a provision of Canon law.
Finally, an act is only a sin if it violates the eternal moral law. But violations of liturgical norms, canon law, and anything that falls under the temporal authority of the Church is not necessarily sinful.
Roman Catholic theologian