Tips from application field
If you configure mappAudit, user roles, and the Audit widget in an Automation Studio 6 project as you remember it from Automation Studio 4, you may face an issue where audit events are not shown. 
Example of AS4 way of configuration
Users and their roles configuration
AuditTrail FUB is enabled, Audit events are recorded
AudtList widget is configured, no error in widget or in logger, but you can not see your audit events 
The cause, or better to say, the change in Automation Studio 6 is that the AuditList MpLink connection is now done via OPC UA. In order to actually see the entries, you have to make sure the OPC UA user logged in has the role BR_Engineer.
Example from AS6:
Role was added to user(s)
So now, a user with the proper rights can see audit events.
Hope this information helps you! 
More info you can find in AS6 Help