The current WT policy only protects the accused.
If reporting to authorities was mandatory, everyone would be protected. The guilty would be punished to the extent of the law. The child would be protected. The innocent would be cleared.
Accusations would not be frivolous if it were known the authorities would be notified. No witch-hunts would exist among the elders. They are, by JW standards, "untrained and unpaid volunteers." The only witch hunts I have witnessed were instigated by such ones. Leave it to the experts. The elders do not claim to be able to heal or diagnose physical symptoms, why do they do the same for psychological conditions?
Mandatory reporting is the only sure-fire way to stop witch hunting....rumour mills among elders' wives aren't.