It would be nice if there was a %composer% tag in the options on the organize tracks dialog (there's probably an overlap with the needed fix for https://bugs.kde.org/show_bug.cgi?id=331443 ) Reproducible: Always
No overlap, no. Adding an additional sorting option is a tad more complex than fixing an untranslatable string.
I had a look. Actually using %composer% tag in organize tracks dialog is possible (It is not listed in the tooltip, as are not some other available tags, but they can be dragged to the scheme by using the drag-drop-tokens-builder to find out their %names%.) so closing.