Actually, the French spelling is "Monseigneur", but the Italian spelling "Monsignor" is pronounced almost exactly the same.
It is entirely possible that (then-Arch)Bishop Taylor had a suffragan bishop. I honestly don't know. I corresponded briefly with Bishop Taylor online but I never spoke with him or met him.
Oops! You are right about the French spelling. The Italian is mio signore, but it is not used for a bishop who is Sua Eccellenza.