This looks good to me, more meaningful than just "Szymanowski" in any case.
This is how Discogs named the release, and I think this is good because the cover makes it much more visible than the composers/works. But if a list of composers/works is preferred I'll change it to that.
I agree that we shouldn't use made-up titles, but in this case "Flute, Guitar and Strings" is used for the CD release on BIS website, even though it doesn't appear on the CD cover. Maybe it should be kept as the release group title ?