Our Lady “never introduced herself as a co-redeemer, rather as a disciple,” Francis said in his December 12 homily for Our Lady of Guadalupe, although Our Lady never introduced herself as a “disciple.”
He vilified introducing new Marian titles and dogmas a “foolishness.” The Church existing before Francis introduced hundreds of Marian titles (e.g. in Marian litanies) and proclaimed four Marian dogmas (Mother of God, Virginity, Immaculate Conception, Assumption).
Attempts to proclaim the fifth Marian dogma of the Co-Redeemer were strong throughout the 20th century but Pius XII vetoed them although this title has been used and discussed since the 15th century.
Pius X invoked it in a prayer which is part of an official Church document (AAS  1914, 108). The title was also used by Pius XI and John Paul II.
(source: Gloria TV)
ACT OF REPARATION
O blessed Virgin, Mother of God, look down in mercy from heaven, where thou art enthroned as Queen, upon me, a miserable sinner, thine unworthy servant. Although I know full well my own unworthiness, yet in order to atone for the offenses that are done to thee by impious and blasphemous tongues, from the depths of my heart I praise and extol thee as the purest, the fairest, the holiest creature of all God’s handiwork. I bless thy holy name, I praise thine exalted privilege of being truly Mother of God, ever virgin, conceived without stain of sin, co-redemptrix of the human race. I bless the Eternal Father who chose thee in an especial way for His daughter; I bless the Word Incarnate who took upon Himself our nature in thy bosom and so made thee His Mother; I bless the Holy Spirit who took thee as His bride. All honour, praise and thanksgiving to the ever-blessed Trinity, who predestined thee and loved thee so exceedingly from all eternity as to exalt thee above all creatures to the most sublime heights. O Virgin, holy and merciful, obtain for all who offend thee the grace of repentance, and graciously accept this poor act of homage from me thy servant, obtaining likewise for me from thy divine Son the pardon and remission of all my sins. Amen. (Raccolta, 1950)