I have some small doubt left about the identification of your cup.
The image of H.CX is certainly identical to the marks on your cup, but in the books I have, the Modena
’s eagle is represented quite differently.
Below I reproduce the marks from the book of Elizabeth Barbolini which deals specifically in silvers of Modena
Also the other mark, the lozenge, does not look like a manufacturer mark in use in Modena
. It looks instead like some marks of Roman silversmiths.
Perhaps they could be fantasy marks used by a silversmith during the long period (1872 1935) in which in Italy there was no law on the hallmarking of precious metals.
Sometimes in the past I found some errors on H.CX, which then were corrected.
You may write to Marina, who is very kind, to ask where she got the information published.