Really, you have no problem with Mary as co-redeemer? Was Mary crucified for you? Do most Roman Catholic receive the image of Mary with the pierced hands as being from God?
There have been various people who have had stigmata through history. It doesn’t mean that they REPLACE, or take the place of, Jesus. It means simply that they have a special co-suffering with Jesus.
Stigmata.
We SHOULD all be crucified, choose to bear our sufferings, choose to carry our cross, as Jesus was, and offer that suffering to God as a sign that we choose to cling to Him regardless of any suffering which might be allowed to happen to us.
Mother Mary WAS “crucified” in the suffering she bore. We are to be like her in bearing our suffering.
Mother Mary does not save us. Knowing who Jesus is while offering our suffering to Him is what saves us. Our Mother Mary, Mother of the Suffering, is provided alive for us in heaven to help us see Jesus qua Jesus and see suffering qua suffering.
If some people won’t accept help from those provided to help us, that is their decision.
To sum up: Mother Mary as stigmatic is not Mother Mary usurping Jesus, but Mother Mary doing what stigmatics do:
“The sufferings may be considered the essential part of visible
stigmata; the substance of this grace consists of pity for Christ, participation in His sufferings, sorrows, and for the same end–the expiation of the sins unceasingly committed in the world.”