[itsme]

"Gruppe" / "group" is technically correct for composers as well. Song properties like collections, setlists, albums, composers, source types, Artists, Genres... (Sammlungen, Setlisten, Alben, Komponisten, Typen, Interpreten, Genres...) set  a kind of label to a number of songs, every song can have many of these properties. This is why "Gruppe" / "group" is used as a generic term for all these properties. Most features of groups are the same or similar and maintained in the same way, described in the manual as group / Group Management / Group Editor (Gruppe / Gruppen Management / Gruppen Editor).

I suppose that at the time when I translated the UI there was "delete group" and "copy group" in the English version and it was changed sometime in English but not in German. But that's just an assumption, my memory might be wrong in details like this.

Anyway, changing the German texts from "Gruppe löschen" to "Löschen" and "Gruppe kopieren" to "Kopieren" is a good idea. It would save some space in the UI and would make the German UI more consistent to the English UI.