Hi Jan. I know some Anglican vicars also use a formula to establish limits too. I know I used a similar formula as a teacher when asked by a child, "can you keep a secret?" or something like that. Clergy/penitent privilege is confidentiality in common law (outside the US anyways..), and sometimes confidentiality isn't the most important thing.
It is complex as you say, and reporting laws are blunt tools which represent a failure of adults to protect children for too long and in too many cases. You're right, there's not going to be a perfect solution. No-one wants to drag a survivor through a legal process, at the same time how does one also ensure they are safe from further abuse and other children are not at risk? There is more leeway with adult survivors for that to be a matter for the survivor, but for children and vulnerable adults then there may only be that one opportunity and there may not be a responsible adult able to act otherwise.
I know some believers will strongly disagree, but I personally don't feel an offender's ability to confess counts for much if children are still at risk. Sadly, if spiritual support on its own worked well for pedophiles, we wouldn't be dealing with so many cases within religions. This may be a case where secular society will have to cut the Gordian knot on this for religions. It will be interesting to see what recommendations come out of the Australian Commission and the Goddard Inquiry for how best to deal with this.