Trying to pin them down on non-reporting is very difficult as they lie about it, deny it and cover it up.
The reason we focus on the two witness rule is because we have them on record, and in print, that they will take an allegation of CSA no further due to this policy.
It also leads to victims being silenced within the community and/or being forced to face their abuser.
The real issue is Witness Culture of no individual's suffering being more important than the reputation of the organization.