The Violanos made after 1916-17 should be tuned to A=440 cps [Hz].
Most of those earlier ones also should be tuned to A=440 cps.

Having worked on nearly four dozen of these machines and owning six
of them myself over the years, I have found the A=440 cps tuning as
advised by the Mills Violano Virtuoso service manual to be correct on
that point.

Another thing that I would suggest, that is to be sure to tighten
all screws in the piano plate firmly before tuning the piano, also
to A=440 cps.

Hal Davis