Every Catholic theologian in history, and every Catholic moral theology manual ever published, and every Catholic catechism ever published, condemns idolatry.
What you are saying is that there is a “secret” Catholic teaching that approves idolatry. This “secret” has been transmitted secretly to several billions of people down the centuries. There are about a billion Catholics alive today, who are in on the “secret,” and they are ALL in on the conspiracy to transmit the “secret,” while managing to keep this “secret” teaching out of absolutely all published material. They have even published thousands of articles and pamphlets that explain that idolatry is a mortal sin, while simultaneously spreading the “secret” teaching to billions of people, without the use of ANY printed material whatsoever. This secret communication system has been kept secret for approximately two thousand years. It has been kept secret by a tight inner circle of billions of people.
What is idolatry to a Catholic???
No not a secret. It's blindness on the part of Catholics. Just like the blindness of the Jews to their messiah. Those who study scripture with guidance from the Holy Spirit see it. Those who study what their elites teach with guidance from their priest or rabbi don't see it.