dirty way of doing it would be to write a script, and then create your launcher to run that script instead
/usr/bin/python /opt/edna-0.6/edna.py -c /opt/edna-0.6/edna.conf &
Save it as ~/edna-script
Then set it executable (+x) then create your launcher to run this script instead.
I think the "Command" field in the launcher editor can't really accept arguments. It assumes you'll just run something like "firefox" or "Terminal"
and not "python <file.py> -c <config_file.conf>