would it be too difficult to have it set up similarly to how you manually add launcher quicklists to the launcher items themselves?
Arrangements=Art1;Media2;Whut3
[Art1 Arrangement]
shortcut=ALT+SUPER+1
launchers= /home/USER/myShortcuts/blender.desktop, /home/USER/myShortcuts/mypaint2.desktop, gimp.desktop
[Media2 Arrangement]
shortcut=ALT+SUPER+2
launchers= /home/USER/myShortcuts/Exaile.desktop, vlc.desktop, mplayer.desktop
launchers= /home/USER/myShortcuts/home.desktop, /home/USER/myShortcuts/chromium.desktop
the user wouldn't really have to type each .desktop into the list they wanted. after creating the arrangement they could simply swap to it and add/remove things like normal.