I search the IFHF's online database at ROOTSIRELAND.IE. It has abt 19 million B/M/D and other records for MOST Irish counties. Records before 1863 are increasingly sparse. By 1800, they are almost non-existant. Many B/M/D events either weren't recorded, or haven't survived.
For Moses, Ruth, and El(izabeth) Jones M 1815 +/- 5 yrs, Co. Cavan, I found 0 records. The choice of forenames and the Jones surname suggest they were protestant. These records are the least likely to survive. Civil registration of protestant B/M/Ds didn't begin until 1845.