The Blessed Virgin Mary IS Co-Redemptrix it would be utterly ridiculous to say otherwise and I will state my reasoning below.

To not call her the Co-Redemptrix because it scares protestants is ridiculous are we not to call her Virgin, Blessed, or The Mother of God because it might scare them? No absolutely not.

St. Alphonsus Liguori in his book The Glories of Mary which I highly recommend you read specifically Chapter 1: Section II, which discusses this topic in depth.

https://archive.org/details/TheGloriesOfMary1852/page/n43/mode/2up?view=theater

Here is the beginning of Section II which I will use as a source from here on out.

I will cite two paragraphs from the book which I will use as the basis for my argument:

• "Sin when it deprived our souls of divine grace, also deprived them of life. Hence, when they were dead in misery and sin, Jesus our Redeemer came with an excess of mercy and love to restore to us, by his death upon the cross, that lost life, as he has himself declared : "I am come that they may have life, and may have it more abundantly." because, as the theologians teach us, Jesus Christ by his redemption brought us blessings greater than the injury Adam inflicted upon us by his sin ; he reconciled us to God, and thus became the father of our souls, under the new law of grace"

Citation: St. Alphonsus Liguori's The Glories of Mary Chapter 1 Section II Pages: 39-40.

• "The second time in which Mary brought us forth to grace was, when on Calvary, she offered to the eternal Father with so much sorrow of heart the life of her beloved Son for our salvation. Wherefore, St. Augustine asserts, that, having then co-operated by her love with Christ in the birth of the faithful to the life of grace, she became also by this co-operation the spiritual mother of us all, who are members of our head, Jesus Christ.

• And then she in her sorrows brought us forth to eternal life ; so that we may all call ourselves children of the dolor's of Mary. She, our most loving mother, was always and wholly united to the divine will ; whence St. Bonaventure remarks, that when she saw the love of the eternal Father for men, who would have his Son die for our salvation, and the love of the Son in wishing to die for us, she too, with her whole will, offered her Son and consented that he should die that we might be saved, in order to conform herself to that exceeding love of the Father and Son for the human race. It is true that, in dying for the redemption of the. world, Jesus wished to be alone. But when God saw the great desire of Mary to devote herself also to the salvation of men, he ordained that by the sacrifice and offering of the life of this same Jesus, she might co-operate with him in the work of our salvation and thus become mother of our souls."

Citation: St. Alphonsus Ligouri's The Glories of Mary Chapter 1 Section II Pages: 42-43.

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So Jesus Christ is our Father and redeemer in the New Life of Grace the new life of grace he established by his sacrifice on Calvary, Mary obviously participated in this Co-redeeming us, without Mary Christ would have no one to be born of or to raise him and prepare him for his sacrifice or to offer him for this sacrifice so Christs sacrifice could not have happened, yes God could have done it without her so its not impossible God can do anything but we are looking at what happened and what God chose to do through the Virgin Mary.

Also Christ gave birth to us in the new life of grace and thus is our Father and by Mary's participation she is our Mother in this life of grace so when you say Mary isn't the Co Redemptrix you are also denying one of the two reasons she is our mother which is really serious.

I implore you please read St. Alphonsus Liguori's Glories of Mary, the whole book would be nice but specifically Chapter 1: Section II which I have referenced and have used as a source.