He may be the Juan Carnago of Calahorra, La Rioja, Spain, who solicited Pope Martin V for prebends in various parishes between 1420 and 1429.
After the death of Alfonso he continued to serve in the chapel under his son Fernando I of Naples.
Cornago was the leading songwriter at the Aragonese court in Naples.
[1] Later in 1475 he transferred to the chapel of Fernando the Catholic who had returned to Spain.
For fuller information see the extensive discography on Spanish Wikipedia.