Perhaps you need to research this a bit more.
As is well known, John Paul didn’t celebrate his own birthday of May 18, but rather his “name day” on November 4, the feast of St. Charles Borromeo, after whom he was named “Karol.” On this day in 1984 the Pope once again calls his Mother the “Co-redemptrix” in a general audience:
To Our Lady—the Coredemptrix—St. Charles turned with singularly revealing accents. Commenting on the loss of the twelve-year-old Jesus in the Temple, he reconstructed the interior dialogue that could have run between the Mother and the Son, and he added, “You will endure much greater sorrows, O blessed Mother, and you will continue to live; but life will be for you a thousand times more bitter than death. You will see your innocent Son handed over into the hands of sinners . . . You will see him brutally crucified between thieves; you will see his holy side pierced by the cruel thrust of a lance; finally, you will see the blood that you gave him spilling. And nevertheless you will not be able to die!” (From the homily delivered in the Cathedral of Milan the Sunday after the Epiphany, 1584). (3)
The next usage of the Co-redemptrix title by John Paul is his most important. At a Marian sanctuary in Guayaquil, Ecuador, on January 31, 1985, he delivers a homily in which he professes the Co-redemptrix title within a penetrating theological commentary of scriptural and conciliar teaching on Coredemption:
Mary goes before us and accompanies us. The silent journey that begins with her Immaculate Conception and passes through the “yes” of Nazareth, which makes her the Mother of God, finds on Calvary a particularly important moment. There also, accepting and assisting at the sacrifice of her son, Mary is the dawn of Redemption; . . . Crucified spiritually with her crucified son (cf. Gal. 2:20), she contemplated with heroic love the death of her God, she “lovingly consented to the immolation of this Victim which she herself had brought forth” (Lumen Gentium, 58) . . . .
In fact, at Calvary she united herself with the sacrifice of her Son that led to the foundation of the Church; her maternal heart shared to the very depths the will of Christ “to gather into one all the dispersed children of God” (Jn. 11:52). Having suffered for the Church, Mary deserved to become the Mother of all the disciples of her Son, the Mother of their unity . . . . The Gospels do not tell us of an appearance of the risen Christ to Mary. Nevertheless, as she was in a special way close to the Cross of her Son, she also had to have a privileged experience of his Resurrection. In fact, Mary’s role as Coredemptrix did not cease with the glorification of her Son. (4)
Only a few months later, John Paul confirms once again the legitimacy of Co-redemptrix. On Palm Sunday, during World Youth Day, the he addresses his “favorites,” his beloved youth, and invokes the aid of Mary under the title of “the Co-redemptrix”:
At the Angelus hour on this Palm Sunday, which the Liturgy calls also the Sunday of the Lord’s Passion, our thoughts run to Mary, immersed in the mystery of an immeasurable sorrow.
Mary accompanied her divine Son in the most discreet concealment, pondering everything in the depths of her heart. On Calvary, at the foot of the Cross, in the vastness and in the depth of her maternal sacrifice, she had John, the youngest Apostle, beside her . . . .
May Mary our Protectress, the Co-redemptrix, to whom we offer our prayer with great outpouring, make our desire generously correspond to the desire of the Redeemer. (6)
In commemorating the sixth centenary of the canonization of St. Bridget of Sweden (October 6, 1991), the John Paul uses “Co-redemptrix” as a title and role understood by this fourteenth century mystic whose revelations did so much to stimulate the medieval development of the doctrine:
Birgitta looked to Mary as her model and support in the various moments of her life. She spoke energetically about the divine privilege of Mary’s Immaculate Conception. She contemplated her astonishing mission as Mother of the Saviour. She invoked her as the Immaculate Conception, Our Lady of Sorrows, and Coredemptrix, exalting Mary’s singular role in the history of salvation and the life of the Christian people. (8)
http://www.fifthmariandogma.com/articles/881/
Pope John Paul never mandated that Catholics believe Mary to be a Co-Redemtrix... there was talk of it during his papacy that even garnered a cover on Time magazine, but the Church decided against it, and the pope’s own statements are ex-cathedra.
If you want to know what the Catholic Church teaches and believes there is only one official source and that is The Catechism of the Catholic Church... perhaps you are the one with a bit more reading to do...
Find me where in the Catechism it uses the term Co-Redemptrix when referring to the holy mother and then your argument may have some gravitas.