The only 'authority' religious clergy have is in regards to sin, not crime.
For it to be a 'confession', it would appear that it would need to be the person who had done the wrong (abuser), confessing his/her sins to the elder.
As the abused party has committed no sin in being abused, would it then be considered a religious confession if the abused party reported to an elder of having been abused?
To uphold and respect 'clergy penitent privilege' and 'confidentiality of confession', matters of confession would need to remain confidential between the confessor and the hearer of the confession. The hearer (elder) could not discuss the confession with another elder unless another elder was present to hear the confession and known by the confessor to be present before giving the confession.
To my understanding, WT's claim to clergy penitent privilege has been ruled inadmissible during some proceedings, due to an elder hearing a claimed 'confession', then sharing the matter with other elders not present when the confession was given.