As far as I know, and I have investigated about that, only three of Alexander's more than 340 works were published:
1. A Choral in A major, published as a manuscript facsimile in Viena by Eberle, 1899 (https://imslp.org/wiki/Choral_(Alexander%2C_Robert))
2. Variations over "Hatikwo", published in New York by Fischer, 1965.
3. 6 Preludes Op.226, published in New York by Mercory Music Co, 1965. (https://imslp.org/wiki/6_Preludes,_Op.2 ... 2C_Robert))
So, apart from those pieces, none of his pieces were published... Apparently. As a example of those publication that are "floating in the air" (as we say in my country) my sources didn't indicated the publishing of the Choral but nevertheless I found the score in the Robert Alexander Collection, and luckily that score had the complete publication date, only was missing the hour when the score left the printer
But, anyways, I really want to know of it's ok if I put all his pieces on PML-Asia or in the Candian Server.