Greetings in that Divine and Most Precious Name of Our Lord and Savior Jesus Christ!
In our writing oriented world of today perhaps we are a bit anachronistic about writings of the past. In the past, things were generally part of oral traditions before they were codified as written documents, even during the Roman era. So the hymns and prayers and chants were popularly sung in the Churches before the books, Gospels, and commentaries were compiled which refer to them. So we know that both the Church and the heresies draw from the same well-spring of inspiration because they are sharing many of the same common experiences and cultures. These stories of Mary were songs and prayers and commemorations before they were books and Gospels, and so we can trust their authenticity. We had this discussion before. These pseudo-Gospels themselves may not be legitimate for various historical reasons, however some of their subjects and details remain accurate because they are mutually confirmed within other accepted books, hymns, and prayers of the Tradition. The Tradition did not copy them from the pseudo-Gospels, the pseudo-Gospels are forgeries, mistranslations, and pulp versions of copies of the stories from the Tradition such as the hymnography, Synaxarium, icons, Liturgies, and prayers.