How to generate a report on Role Administration?
Perform the following steps to generate a report from Role Administration events:
When you click on any one of the recent events based reports, a dialog will appear as shown below, for user selection, whose events you would like to see in the generated report

 
If you would like to view events for a specific user, select the "Specific users" option, and select the list of users by clicking on the "Select users" button

 
For Top users based report, a dialog will appear as shown below for selecting events and date range for fetching the list of top users who had performed the role administration events recently
 
Once you click on "OK", the report will be generated like all the other Audit Reports.