@mitu Actually it turned out all I needed to do was edit ES_SYSTEMS.CFG and it all just worked. Weird, I thought I'd already tried that.

@Retro-Arcade-Fan
Last I looked it was still part of the setup script. Can’t remember if it’s an experimental/optional package though. But it does work. Just scraped with it the other day.

Great. That worked. The configuration has been saved to the file.

Regarding the theme for the Commodore 128...

I have found the Commodore 128 system logo from UDb23 (c128_ingo_udb.svg)
Is there also a keyboard image (red) for the C128 available like for the C64?
I haven't found anything yet.

Then my system integration into ES is nearly perfect. :)

Thank you for the support again it was a great help to sort out the errors!

Has anyone managed to make Cartridges work for Vic-20? With Vice there is the possibility to add the -cartgeneric parameter, but I tried with lr-vice and it doesn't work.