I think it's more the locking pawls than incorrect key barrel assembly. The first time I pulled the bags on my bike before riding it home, they came right off.
Blunt the points of the locking pawls a bit with a file, testing as you go so you don't destroy it. Clean it and add just a dab of graphite on the inner surface.
...or, just keep making the dealer replace them under warranty. Eventually, Ducati will fix it or go broke.
As for the purple hue, I thought mine had already faded but realized it was just my polarized lenses. When I look under shades, they are still black. My seams are spreading and I have a number of frontal impact holes/tears...but, I still like them.