it doesn't sound like you're using proton's run file
did you add this to steam's launch option for FA ?
PROTON_NO_ESYNC=1, PROTON_DUMP_DEBUG_COMMANDS=1 %command%
the PROTON_DUMP_DEBUG_COMMANDS allows for the creation of a run file under /tmp/proton_$USER/
you copy that file to you faf install dir and point to that file as the run arg for FA.