I don’t know, maybe you should read what the Popes themselves said about the Magisterium. And I will include all true Popes up to Pius XII here because I, unlike you, believe that their teaching on the Magisterium was consistent.
This begs the question because they didn't technically define what the Magisterium is. Unless you take the implied definition, due to their repeated use of the word "teaching". And what is a "teaching"? It is an authoritative, obligatory fact which all catholics must believe to be saved.
We know V2 (and arguably, 99% of their acts/words since 1960) have not risen to the level of formal teaching. Thus, V2 and post-V2 writings/sermons/docuмents etc are not part of the Magisterium (properly and Traditionally understood).
The V2 and post-V2 writings/sermons/docuмents etc would be part of the NEWER/MODERN level of "ordinary, fallible magisterium" which did not exist prior to the 1900s.
Pope Pius IX clearly articulated what the Magisterium is in Tuas Libenter: "...all that has been handed down as divinely revealed by the ordinary teaching authority of the entire Church spread over the whole world, and which, for this reason, Catholic theologians, with a universal and constant consent, regard as being of the faith."
This sums it up perfectly.
1. Did V2 claim to be "handed down" from Tradition? Parts yes, parts are also admitted to be novelties.
2. Did V2 claim to be "divinely revealed" by the teaching authority of the Church? Nope.
3. Did V2 claim to explain, clarify, define or teach anything as being "of the faith"? Nope.
Therefore V2 is not part of the Magisterium, as defined prior to the 1900s....which is the time period when Pius IX lived.