I am assuming the location of Cappaduff mentioned on the extracted records is actually Cappaghduff. This is in the Civil Parish of Ballyovey (usually the same as the Church of Ireland Parish), and is located on the western edge of Lough Mask in Co. Mayo.
The civil birth certs should confirm if this is the right place.
Even though the town of Ballinrobe is the far side of the lake it is the registration district for Cappaghduff. See google map :
Ballinrobe to Capaghduff This fits with the registration district included on the BMD index records found for the potential births.
It doesn't look promising for Church of Ireland records for the dates you need. Allowing for the spelling variation, I think these are the details available for this parish in the RCB Library :
Parish Ballyovie
Baptisms 1879-1951
Marriages 1854-1954
Burials 1880-1966
It could be that there was another CofI church on the area before these years..
Shane