...two interesting texts on obedience.

This seems to be the principle in a nutshell:

Human authorities, even those instituted by God, have no authority other than to attain the end apportioned them by God and not to turn away from it. When an authority uses power in opposition to the law for which this power was given it, such an authority has no right to be obeyed and one must disobey it.

I don’t know whether it comes from an error in translation, but there seems to be a mistake in this bit:

This holds true for everything that the recent popes have commanded in the name of Religious Liberty or ecuмenism since the Council: all the reforms carried out under this heading are deprived of any legal standing or force of law. In these cases the popes use their authority contrary to the end for which this authority was given them. They have a right to be disobeyed by us.

Surely, it is incorrect to say:

They [the recent popes] have a right to be disobeyed by us.

I accept that this statement should be read in context. That is to say, it was meant to be understood only in relation to what “the recent popes have commanded in the name of Religious Liberty or ecuмenism since the Council”.

Nevertheless, what can it possibly mean to say “they have a right to be disobeyed by us”?

I suggest that what the Archbishop most probably meant here was:

[In these circuмstances,] they [the recent popes] do not have a right to be obeyed by us.