Is the Pope culpable for sex abuse in the church?
I would guess he is. The institution is far more important to the clergy than the people it claims to serve. I have seen this repeatedly in my life. That's why I am a Unitarian Universalist Roman Catholic and not just a Roman Catholic. Jesus would be ashamed of the church which claims to channel Him. There are many examples of the church being morally deficient. It has sometimes apologized for its mistakes in the past after centuries as in the case of Galileo and decades as in the case of anti-semitism against the Jews but only after the stench of hypocrisy has become so strong that the Magisterium has little choice if it is claim any moral credibility at all.
It is interesting that it is the secular authorities which has brought the church to account and not the church itself.