In CL you can run RTVJOBA and get
CL var for USER (10) . . USER
CL var for CURUSER (10) . . CURUSER
In RPG you can run a simple SQL, VALUES CURRENT USER INTO :CurrentUser
Use Current User instead of User in your trigger program.
Trying to reconfigure RSS for each and every user, and then start running into the same issue with other client applications, is a pointless waste of time versus just fixing the trigger program.