My first thought would be to use the CA Agile Central Excel Add-in.
Create a new query.
Query
Type: Artifact Change Notification
Filter: Creation Date _ your choice here
Columns: leave blank
Run Query, then filter the results in excel by the Description column
Use the "Text Filter" & Contains option
Enter into SCHEDULE STATE changed from [Completed] to [Accepted] into the Custom AutoFilter box.
The User column gives you the name of who accepted the user story.
Let me know if you need visual aides.
- Michael