The contents of volume 2 have been announced: Clara Kathleen Rogers' sonata op.25 from 1888, Albert Stoessel's sonata in G major (ca.1920), and Julius Chajes' sonata in A minor (published 1944). (https://toccataclassics.com/product/lost-american-violin-sonatas-volume-two/) I think the Rogers and at least one of the two others have received a recording before but lost is still not for from the case, I expect... (Edit: the Stoessel has been recorded commercially too, but not, far as I can tell, the Chajes.)
Rogers received her early training from her father, the English musician John Barnett (composer of one of the first English Romantic operas, The Mountain Sylph...overture relatively recently recorded by Bonynge). She also sang opera for a number of years under the stage name Clara Doria, iirc. Her memoirs are quite interesting....