I presume Tradidi meant to say "This clearly disproves Mary of agreda's claim that Our Lady had infused knowledge."
The confusion is caused by Nadir attempting defend Mary of Agreda's "Mystical City of God" by confounding with that work a quote actually contained within Valtorta's "Poem of the Man God."
In other words, it is Valtorta, and not Agreda, who contended that Mary had infused knowledge from the age of 3, and Fr. Lafitte subsequently proving such could not be the case (and not by observing the "because I have not known man" phrase which Nadir seizes upon, but by the "how shall this be done" (i.e., the Incarnation) phrase.
If Mary possessed infused knowledge, than the means by which our Lord would become incarnate coud not have been unknown to her (as it clearly was).
So in summary, Nadir has made two mistakes:
1) She confounded Agreda's "Mystical City of God" with Valtorta's "Poem of the Man-God;"
2) She thought Fr. Lafitte was referring to the "because I know not man" phrase to make his point, when he was actually referring to "how shall this be done" (i.e. the Incarnation, the means of which Mary was ignorantuntil Gabriel told her).