I'm not aware of anything being audited however we have instead introduced the option for a review when setting up a policy. If you set a mandatory review for the policy that will ensure all docs the policy was applied to enter 'Awaiting Review' state. The authorised reviewer(s) must then approve or reject the review before the policy will execute. Without this review being approved no docs would ever be destroyed by accident.
The Execute Policies.log will show a count of docs awaiting review at any given time.
25/11/2020 23:37:56  Info SqlDiscoverer 'delete with review' (7), phase 'Dispose' (7) : 1 documents awaiting review
So if files are missing you know who to contact - the designated reviewers since they had the final say and must have approved the review. The relevant connector delete.log will also show when the delete(s) took place if they were approved.
One further thought is we do offer a facility to notify policy approvers via email.
You could get this email sent to an address that is always saved. That way you have a record of who was emailed to approve reviews etc.