Where can I buy barley semolina (semoule d'orge) in the U.S.?
I would try a pan-Asian grocery store; H-Mart and Assi are two pan-Asian chain supermarkets. Or try a Middle Eastern food store, like Kalustyans in NYC, who also ship. Have you already looked on Amazon?
I Googled Bob's Red Mill Barley and Bob seems to offer several Barley products. Maybe one will work for you.
I found barley flour (a fine powder) and barley grits (a course grind) at a middle eastern market. Not sure if either product is the same as 'barley semolina'