Privileged communications are just that. You could make much stronger criminal cases if you could be privy to every conversation between client and attorney , but you can´t.
In the cases you mention a priest could talk about the problem in general to someone in authority without breaking the seal of the confessional, and that person COULD investigate the problem in general, netting the miscreant.
The state has no business being involved in a religious sacrament. This holds true for Protestants, Catholics, Jews, Hindus, anyone who practices a religion with an established ¨priesthood¨.