I've been having a very close look at the Papers Past collection to see if I could find some evidence that George Griffith was ever in New Zealand, and I think I have found it, in the above advertisement for:
"Pianos. G Griffith from Melbourne, pianoforte Tuner and Repairer, Address - R Wright, Victoria Hotel, Revell street, [Hokitika]", followed by "Music provided for Balls and Parties, Violin and Piano always at command. J R Wright, Victoria Hotel."
A series of advertisements was placed in the West Coast Times from 8 October 1867 to December 1867. George seems to have some form of business relationship with J R Wright of Hokitika. I feel he is likely to have been the "violin on command".
Mr Wright appears as a supporter of various candidates for the Provincial Council from 1866, so he had perhaps been in town a little longer than Griffith.
I'm pleased to have been able to spot him somewhere, at least. And of course if you are a connection of J R Wright, I would love to heard from you. Maybe one of my unknown gentlemen is J R Wright.