Yes, I agree with you; obviously Jesus is God and Mary is not God. The way I read it in the Catechism is that there is a Treasury of Grace. The Treasury of Grace is eternal and came from the Death and Resurrection of Jesus. Mary and the Saints, because of their faithfulness to God and their good works have added to the Treasury of Grace. The impression I got from reading that is that Mary and Saints added a limited amount to the eternal Treasury of Grace that we have access to.
The Catechism is very interesting in how it explains that the entire time since the dawn of creation until now is just 1 day. It is the day of the Passover of Jesus. We are still in that same day and the impression I got from the reading is that we are sharing the sufferings and the glory of Jesus. I find it all very fascinating and awesome.
That opinion is anti-Scriptural;. There is nothing in the Bible about Mary or anyone else "adding to the Treasury of Grace."
However there is plenty of Scripture which tells us Christ alone redeems His flock.
In whom we have redemption through his blood, even the forgiveness of sins: Who is the image of the invisible God, the firstborn of every creature: For by him were all things created, that are in heaven, and that are in earth, visible and invisible, whether they be thrones, or dominions, or principalities, or powers: all things were created by him, and for him: And he is before all things, and by him all things consist." -- Colossians 1:13-17 "(God) who hath delivered us from the power of darkness, and hath translated us into the kingdom of his dear Son: