I was told that the presets were available via the editor software, but I was unable to find them though I have the editor already installed.
However, I found another way to restore the factory presets: "Just" (re-)update the firmware of the Uno Synth Pro and it will contain the original factory presets.
I'm happy I had the idea with the OS update, so the problem is now finally solved for me.
Thanks a bunch,
ce