Is Mary the Coredemptrix or Mediatrix?
The quick answer, she is neither...
Coredemptrix and Mediatrix are titles given by some to Mary who believe that she plays a vital if not direct role in mediating between God and man including salvation as well. But Mary was not as perfect as some want to make her out to be. Scriptures in several places indicate clearly that she was as much in need of a Saviour as any other person who ever lived. She even said so herself when she referred to God as her Saviour just prior to Jesus' birth. And Mary said, My soul doth magnify the Lord,  And my spirit hath rejoiced in God my Saviour. Luke 1:46-47 Something happened with Mary between the birth of Jesus and Acts 1:14 that prompted Jesus to indicate that she was not doing the will of His Father in heaven nor was she hearing and keeping His word. She definitely was not perfect and needed a Saviour. While he yet talked to the people, behold, his mother and his brethren stood without, desiring to speak with him.  Then one said unto him, Behold, thy mother and thy brethren stand without, desiring to speak with thee.  But he answered and said unto him that told him, Who is my mother? and who are my brethren?  And he stretched forth his hand toward his disciples, and said, Behold my mother and my brethren!  For whosoever shall do the will of my Father which is in heaven, the same is my brother, and sister, and mother. Matthew 12:46-50 (see also Mark 3:32-35 and Luke 8:29-22) And it came to pass, as he spake these things, a certain woman of the company lifted up her voice, and said unto him, Blessed is the womb that bare thee, and the paps which thou hast sucked.  But he said, Yea rather, blessed are they that hear the word of God, and keep it. Luke 11:27-28 Then there was that awkward exchange in John chapter 2 verses 3 through 5: And when they wanted wine, the mother of Jesus saith unto him, They have no wine. Jesus saith unto her, Woman, what have I to do with thee? mine hour is not yet come. His mother saith unto the servants, Whatsoever he saith unto you, do it . So Mary definitely was not always a perfect person and certainly she is not even close to being qualified as a Coredemptrix nor the Mediatrix that some claim she is. She was a sinner who needed a Saviour as much as anyone else. Jesus saith unto him, I am the way, the truth, and the life: no man cometh unto the Father, but by me. John 14:6 For there is one God, and one mediator between God and men, the man Christ Jesus;  Who gave himself a ransom for all, to be testified in due time. 1 Timothy 2:5-6
This should also make it clear that from a scriptural standpoint that the so-called immaculate conception is pure heresy...This is the belief that Mary was born perfect and without sin and was thus sinless when she conceived Jesus.
Read your Bible and pray more and stop listening to the Nope, I mean Pope, and start listening to God's Word instead.