I grew up within a stone's throw of Coughlanstown graveyard which is adjacent to Stonebrook Petting Farm. The church (RC), which is now in disrepair was decommissioned perhaps in the 16th or 17th century - I have the date written somewhere if of interest. The old parish of Coughlanstown incorporated the townslands of Donode and Coughlanstown itself, which are both part of Ballymore Eustace parish today. There have been people buried here as recently as 2009 but these people were all very local. I would say you have to go back to the 19th century for Coughlanstown cemetary to have been used on a more widespread basis. There are a few clear headstones but not many and my guess would be that people buried here would have been resident in Coughlanstown, Harristown, Mullaboy, Donode, Mullaboden, Stonebrook, Susheen townslands rather than the wider Ballymore Eustace parish. Besides the main cemetary in Ballymore Eustace which is newer, there were people buried in Ballybought (which is very hard to find) and Tipperkevin as well as Coughlanstown and Hollywood.
I have heard that a Treacy family were the caretakers to that church. They lived in Coughlanstown and retained the key long after the church was decomissioned. The last surviving Treacy was buried in the 19th century in the graveyard with the key.