The Roman Catholic Church calls themselves the universal church. There is the universal church and the local church (locality expression, Biblical locality), but the Roman Catholic Church is not the universal church, but the great harlot of religious Rome, that makes drunk the nations with the wine of the wrath of her fornications (Rev. 14.8).

""Roman Catholics do not actually pray to Mary" - Yes they do.

Hail Mary,
Full of Grace,
The Lord is with thee.
Blessed art thou among women,
and blessed is the fruit
of thy womb, Jesus.
Holy Mary,
Mother of God,
pray for us sinners now,
and at the hour of death.

Catechism of the Catholic Church admits that prayers to Mary are doctrinal:

2675 Beginning with Mary's unique cooperation with the working of the Holy Spirit, the Churches developed their prayer, centering it on the person of Christ manifested in his mysteries.

2679 Mary is the perfect Orans (pray-er), a figure of the Church. When we pray to her, we are adhering with her to the plan of the Father, who sends his Son to save all men. Like the beloved disciple we welcome Jesus' mother into our homes, for she has become the mother of all the living. The prayer of the Church is sustained by the prayer of Mary and united with it in hope.

Sacraments for Salvation?

Catechism states the following (it is unclear whether works is meant her for new birth or for overcoming in Christ. Works for overcoming in Christ is true, but not for true for new birth):

1129 The Church affirms that for believers the sacraments of the New Covenant are necessary for salvation.

See Ephesians 2:8-9