I recently heard a theologian assert that Hmanae Vitae is not infallible teaching, although it is important. This seems to be a good read in support of the encylical: https://www.ewtn.com/library/Theology/AUTHUMVT.HTM. Sometimes, reading about arguments of this sort bring to mind one word: wrangling. Splitting hairs might also be apt. Such discussions are important, perhaps, but they can seem too academic. It reminds me of teenagers trying to wriggle out of what Papa had said. :-) (That was how we addressed our father, growing up: Papa. And we probably did that sort of wrangling then, too, at least some of the time!)
But following the evidence, and we have plenty of it, it does seem that Pope Paul VI was proven right for the most part, and I don't see that he was wrong anywhere.