The only outcome of this law will be sting operations by undercover cops to frame priests.
Real guilt-ridden sex abusers (if there is such a thing) will cease talking to any priests any where any time.
The real mandatory reporting void is where most child sex abuse exists - in the home. An abusive male relative will do anything to keep a secret. So they aren't going to report their suspicion about another pedophile (masquerading as a priest) for fear that police psychologists might ask that same child probing questions about whether anyone had "ever done that to you before?"
Ask yourself - why is so much emphasis being placed on priests to report what they heard from someone who heard it from someone who heard it from...
20, 30, 40, 50, years of testimony from people (allegedly) who told the Bishop but never told the police. WHY?

"...a liar would have told a more believable story."

Now there's a paradox.

insidestory.org.au/judges-doubts/

You are wrong. Cardinal Pell has emphatically denied the accusation in court, just as he has outside court. (Most pedophiles plead guilty).
And every legal expert in Australia has agreed that Pell would have been instructed by his barristers NOT to take the stand.
One of the reasons that delayed accusations...decades old child sex abuse cases... are hard to prosecute, is because child victims typically can't remember sufficient detail (under cross examination) to attain the burden of proof beyond all reasonable doubt. The passage of time generally leaves victims with recall of only the sex act trauma itself - not day, date, time, what color were the curtains, etc etc.
But in the Pell case the accuser had an extraordinarily uncharacteristic level of recall - in vivid detail.
So the uneducated juror mistakes this for "credible testimony" when what they should have realised is that something is not quite right here.