“With the arrival of a new production of “Fiddler on the Roof” on Broadway, some commentators have again assumed that the show’s value lies in its authenticity. Early responses to the revival have gone so far as to count the Jewish names in the cast and crew, noting incredulously that even the role of Tevye is played by a non-Jewish actor, Alfred Molina. This is hardly surprising: the further removed we are from the Old World, the more we long to recapture it. But what is surprising is that the pseudo-klezmer tunes and schmaltz-laden accents in “Fiddler” were ever assumed to be the real thing.”