You’d have to demonstrate the catechism is proclaiming their subjective experience to be objective reality, but it can’t otherwise it’s heresy. There is no concord between the objective reality of who God is which has been revealed to Christians alone, and the fantasies invented by men. They simply do not REALLY match, except perhaps accidentally and by a vague intention.
Catholic tradition is a bit more comprehensive than the compilation of a catechism from 1992. How about the catechism from 1990? But that would be the Roman Catechism. And if you read the intro of the CCC it clearly says it does not abrogate any currently approved catechism.
3rd paragraph from the end of the Apostolic Constituotion Fidei Depositorum by JPII-
“This catechism is not intended to replace the local catechisms duly approved by the ecclesiastical authorities, the diocesan Bishops and the Episcopal Conferences, especially if they have been approved by the Apostolic See. It is meant to encourage and assist in the writing of new local catechisms, which must take into account various situations and cultures, while carefully preserving the unity of faith and fidelity to Catholic doctrine.”
Interesting. So if other catechisms teach it is a sin against faith to worship with Protestants and schismatics and adherents of false religions, what is it to admit they OBJECTIVELY and in reality have the same God as us?
A heresy. Nostra Aetate is speaking of subjective impressions of non-believers, not objective reality of their belief.