As to “Mediatrix of all graces”, Pope Pius XI used this phrase here:
Encyclical On the Sacred Heart
CARITATE CHRISTI COMPULSI
“… Let the faithful hasten in large numbers to the eucharistic board, hasten to the foot of the altar to adore the Redeemer of the world, under the veils of the Sacrament, that you, Venerable Brethren, will have solemnly exposed that day in all churches, let them pour out to that Merciful Heart that has known all the griefs of the human heart, the fullness of their sorrow, the steadfastness of their faith, the trust of their hope, the ardor of their charity. Let them pray to Him, interposing likewise the powerful patronage of the Blessed Virgin Mary, Mediatrix of all graces, for themselves and for their families, for their country, for the Church…”
Here’s what I found (at christendom-awake.org/pages/marian/5thdogma/titlemag.htm)
Pius X further expands the panoply of Marian titles used by Pope Leo XIII. Going beyond the Marian titles of Mediatrix, Conciliatrix (Conciliatrix), Restorer (Reparatrix), and Dispensatrix of all grace, Pope Pius adds to the Mariological development when he sanctions the use of the word “Coredemptrix” by three Congregations of his Curia: In the Congregation of Rites, we see the decree elevating the Feast of the Seven Sorrows of the Blessed Virgin Mary to the rite of a double of the second class: “Through this decree…may devotion to the merciful Coredemptrix [Conredemptrix] increase.”  The Holy Office repeats the title in the following section on Indulgences:
There are some people whose love for our Most Blessed Virgin inclines them never to pray to Jesus without mentioning the name of His mother, Blessed Mary, our Coredemptrix [Corredemptrice]. This laudable custom expands the invocation, or the Christian salutation: “Praised be Jesus Christ,” concerning which this Congregation issued a decree on March 27, 1913. 
Six months later the Holy Office again employs the use of this term:
An indulgence granted to the following prayer for reparation addressed to the Blessed Virgin Mary, the instrument of reparation [reparationis causa]: “Blessed be your prerogative…of Coredemptrix [corredentrice] of the human race”.
We can do more than presume that Pope St. Pius X personally approved their statements. After all, they were published in the official Acta Apostolicae Sedis and were never recanted. As cited above, on one occasion “Coredemptrix” was used by the Congregation of Rites, but twice this title passed the scrutiny of the Holy Office, the very congregation commissioned and entrusted to insure doctrinal integrity. Therefore, we see here the Magisterium’s first three endorsements of Mary’s title “Coredemptrix” with an indulgenced encouragement to the faithful to recognize her blessed prerogative as “Coredemptrix of the human race.”
I think the Church approves and commends the usage of these titles. Whether and when the underlying truths need to be dogmatically defined is up to the Church.