heh, this is one reason why you want am artist with good color experience to do things like accurate preservation efforts (pinball art...) ,rather than a person whos not too color savvy, and has little experience with using them.
Im somewhat shocked at the variances in results though. I assumed that may be slight differences... but the range of results is quite vast, all over the map.
Edit: Took the test. Got a Perfect

A little surprised, cause there were a few tones that were really tricky to tell apart.