A very interesting interview: James Loeffler, pianist and scholar, discusses how Wagner's antisemitism affected Jewish composers and musicians in Europe (most certainly including the composers in my project).
"James Loeffler is an associate professor of history and Jewish studies at the University of Virginia. He is a trained pianist, ethnomusicologist, and specialist on Jewish classical music. In our latest Voices on Antisemitism podcast, Loeffler discusses German composer Richard Wagner's antisemitism. The influence of Wagner's ideas on Adolf Hitler is well known, but as Loeffler explains, Wagner's antisemitism also adversely affected Jewish musicians in Europe during the late nineteenth and early twentieth century. "
Another article that may interest you after listening is this one on Forbidden Music, by Michael Haas, which discusses Mendelssohn, Mahler, Zemlinsky, and Schoenberg with relation to Wagner's legacy.
"Mahler did represent one Wagnerian trait that would be passed on to future generations of Vienna’s Jewish composers: he was not a performer on the piano or violin, or indeed, any instrument. Wagner resented the fact that all of the prominent Jewish composers of his day happened to be virtuosi: Meyerbeer, Hiller, Mendelssohn and Rubinstein dazzled as pianists. Indeed, it was the only means by which a Jewish composer could be noticed. Neither Mahler, Schoenberg or Schreker claimed to be more than competent on any particular keyboard or stringed instrument. Zemlinsky was a marvellous pianist but this was not his means of establishing his compositional credibility. This sea change is important as all of these composers developed a uniquely fine ear for the ‘distant sound’ that defined fin de siècle musical Vienna."