See Presto Classics (https://www.prestomusic.com/classical/products/9503348--alberto-williams-violin-sonatas-nos-2-3). (His three violin sonatas date from 1905, 1906 and 1907; these are the latter two.) Release is expected in about two months.
Thanks, Eric. I'd spotted this and then forgotten about it!
I'm assuming btw I'm not making a "should have read more carefully" mistake and that it didn't say he wrote 3 violin sonatas (1905-7) and -then- these 3 later ones, or something, will double-check that today. At least one of the sonatas performed on this disc is performed (by someone else iirc) on YouTube.
I heard a symphony of his years ago on this much-much-missed weekly radio program* devoted to less known music (from all musical eras, from the host's collection; much of it Romantic but not all. The symphony, from I think an Arte Nova CD, was late Romantic and enjoyable; we may have discussed it here...)
*maybe out of WEOS Hobart & William Smith College(s) (Geneva, New York, US), which was close enough to here for a good radio to pick up if not ideally.