WCC 11.x to AutoSys 11.x - the commandsponsor (igateway) is contacted/required and used on the AE host for ECLI and Forecast.
WCC 12.x to AutoSys 12.x - there is no igateway / commandsponsor on the AE host anymore as of r12.
The ECLI and Forecast are funneled to the AEWS on the AE Server.
If you have WCC 12.x communicating to an AE 11.x then WCC will contact AE 11.3.6.x's igateway for ECLI/Forecast items when working with that specific AUTOSERV.
NOTE - there is still a AutoSysCommandFilters.txt file on the AutoSys 12.x system which you can use to control what commands the ECLI can execute.
NOTE - Additionally there are EEM policies which also then determine which commands the users can issue thru ECLI.
So you need the command to be present on the host, it must be listed in the AutoSysCommandFilters.txt file, and you must have access to it via the EEM policies.
And you still do need a credential user for the backend to execute the commands eventhough the authorization is done against the logged in wcc user.