/opt/retropie/roms/snes isn’t the right folder. it shouldn’t even exist!
if memory serves, the /opt/ directories should just be
/opt/retropie/emulators (the actual executable files for the various emulators)
/opt/retropie/configs (the config files for the same)
all roms are transferred to and run from /home/pi/RetroPie/roms – the contents here should match what you see in emulationstation.