“The Catechism is not supposed to replace liturgy, devotions, or faith formation.”
I would hope not, though in honesty do you think that what passes for liturgy and devotions in most Western Latin parishes doesn’t do more harm than good when it comes to forming true and devoted and understanding members of The Church? Clown Masses, heck, even Masses where the priest sort of makes up the rubrics as he goes along, are destructive; they are obstacles to the formation of a Christian mindset. To substitute a communal, liturgical prayer life with the catechism is likewise destructive, though if the liturgical life has been distorted, as it certainly seems to have been, maybe the catechism is the best tool you have left. But the result won’t be good.
Again, while liturgy has declined at roughly the same time that the Catechism was written, the Catechism is not replacing the liturgy. In fact, if the clergy better internalized the Catechism, we’d see less liturgical abuse.
A disconnect between the Mass and the Catechism can only be confusing and counterproductive. When you have more than one Mass, how can you have the same Catechism?