Hello,
I have checked and we can retrieve the ACS Passed/Failed authentication from the CLI using the following commands:
acs81/acsadmin# sh acs-logs
The above command will list the available filenames from the ACS logs. We might want to focus on the ones that include "acsLocalStore.log"
Then we can execute:
acs81/acsadmin# show acs-logs filename acsLocalStore.log
The above command will list the Authentication attempts reports on the CLI output. It might not be a friendly way to review them but you can copy/paste on Notepad++ or any other Text Editor and look for the Username attempts that way.
If this was helpful please rate.
Regards.