Trolling through my Helen Creighton books, I found four songs with Cape Breton affiliations and no known author. All these are in MARITIME FOLK SONGS, Ryerson, 1961:

P. 33 - A Bonny Ca' Laddie For Me
p. 185 - Springhill Mine Disaster (ie, that of 1891)
p. 187 - Along The Shores Of Boularderie (it's not got much Gaelic)
p. 210 - The Hills And Glens

The Springhill song is in Digitrad. Mr. Google seems to have heard of "Laddie" and "Shores".