@deodekabokat If you're on the command line, you can use mc (maybe you're familiar with the Norton Commander/Dos Navigator/etc. interface) and navigate around the filesystem.
Otherwise, you can copy the file on the ROMs folder and look at it over file shares

cp /etc/emulationstation/es_systems.cfg $HOME/RetroPie/roms

I'd advise to use the full image - and not the Berryboot variant - if you can spare a SD card for a few days while you tinker with RetroPie.

****** SOLVED: *******
In Vice i used "reset settings to defaults" and now Tape-Images are loading!
But i am afraid to say the "save settings" option is not really reliable/stable (i can "save" changes of my settings - but at the next start the changes are gone... Have to check that now....