The Catholic diocese of Finisterre in Brittany has a digital library here. Among this material are many volumes of the “Cornish Saints” pamphlets, issued by Gilbert Doble in the 20s and 30s. Just search for “Doble” in the search bar, and up they come – 46 of them.
I stumbled on this by accident, and the series is not complete. But it does include some of the ultra-rare French translations that he did. For Cornish saints are often honoured in Brittany also. Well worth knowing about!