And so, Church teaching needs to be accepted by the sensus fidelium in order to rise to particular level of assent.
And that brings us back to a particular teaching about sexual ethics that has, IMO, not been fully been accepted by the sensus fidelium . (The sense of the faithful including bishops, priests, religious, and lay people.)
On what basis do you make this assertion, and what do you mean by “particular level of assent”?
The Church is not a democracy, Catholicism is not democracy, and Christianity is not democracy.
If a large portion of the faithful — even including priests and bishops — reject what the Church teaches on this point or that, it does not affect the truth of the matter, nor its binding force, one iota. They are wrong and the teaching Church is right. They are the ones who need to change, not the Church.
I take it you are referring to the reiteration of the Church’s teaching on birth regulation in
Humanae vitae (1968). Here you had a novel concept — being able to use artificial means, means that were now efficient, effective, not unpleasant to use, to customize the size of one’s family and to have sex pretty much on demand without consequences — a “shiny new thing”, as I have elsewhere referred to it — and Catholics wanted to be able to use it. Pretty enticing, wouldn’t you say? All Christians had condemned contraception until the Anglicans approved it at the Lambeth Conference in 1930. In the wake of Lambeth, the various Christian confessions dropped their objection. Catholics saw other people using it, having easier lives as a result, said “they do it, why can’t we?”, and in short order, made up their minds “there is nothing wrong with it”. It’s pretty obvious what happened then. They became emboldened to dissent from Church teaching, not infrequently because priests told them they could do that. They refused to accept the teaching, convinced themselves that they were still good Catholics (again, with the encouragement of priests and other teachers), saw that the sky didn’t fall as a result of their disobedience —
“non serviam!” — and there you had a large wing of the Church, centered in the affluent societies of the West, refusing
en masse to accept the Church’s teaching. Here you had people in large numbers, emboldened by the consensus of society outside the Church, making up their minds about what they were going to believe, and what they were not going to believe. As I always say,
"the tail wagging the dog".
This did not affect the truth of the Church’s teaching one iota. Again, the Church is not a democracy, and the truths of Catholicism do not depend upon the consent of the faithful. The teachings of the Church are what they are, and if people — even large numbers of people — choose to disbelieve them or not to adhere to them, that is on those people, not the Church.