Welcome to Ireland Reaching Out!
There is an alternate name for Kilskeery parish-- Trillick and Trillick records are included in the Roots Ireland data base. Here is a link to the parish register for 1840-1880. https://registers.nli.ie/parishes/0315
This link takes you to the particulars for the current parish of Trillick which is in the Diocese of Clogher https://www.clogherdiocese.ie/parishes/parish-details/?parishID=35 Hit the Parish Team link to see more particulars on the parish priest and other info.
We have a Northern Ireland expert so I will let him assist you with your Tierneys and O'Neills.