Is there an audit trail for custom review states?

Yes. To see the audit trail, in the bottom-right corner of a custom view or the Record Listings view, click the arrow button (^) to expand the Details pane.

All custom review states are available for use by the InForm rule package so that rules can be designed to set or retrieve the custom review states. In the audit trail, any changes made by the rule package on the custom review states are marked as user Autoquery.