At least two of my Leyden great uncles were born in Miltown Malbay. Martin and Patrick. They came to the USA while still children in 1870.
I am also in touch with another Leyden who has knowledge regarding the Leyden pub in Inagh. (I wrote him a note regarding your post here). There is a picture of Leyden's Pub in the closed "Leyden Genealogy" facebook group. (Please "friend" to join. You cannot see anything until you are accepted). If you check for the posts around Feb 9th there is conversation and a pic of Leyden pub.
There is at least one Norah, Mary, and Joseph in our Leyden tree as well.
I hope we find the connection to our Leyden's! Please keep in touch Peggy