Being accused of a crime by a child, any answer to the elders made by the accused would not be privilege.
Spontaneously (and prior to accusations) fully confessing such a crime, once reporting to HQ, privilege is lost. You don't really believe they report and leave his name out, do you? Seeking guidance for an anonymous person- maybe it still fits the privilege definition, providing that Watchtower actually admits to having a clergy class like many other Christian denominations.
And, in my opinion, even a full confession loses the privilege status once the matter goes beyond just congregation elders in the investigation stage- approaching the child with their guardian.
Clergy privilege is meant for believers to come clean with God and basically add the clergy person to their 5th Amendment right (or similar right to avoid self-admitting a crime).