There is currently no report available for emails being released from the quarantine, these would need to be fetched from available logs.
There is an enhancement request to track it, which you can work with your Accounts team to prioratize for future releases.
https://bst.cloudapps.cisco.com/bugsearch/bug/CSCvc80746
Emails going into quarantine due to filters certainly do have reports specific for content filters and message filters.
Regards,
Libin