In case you ever check in, I'll leave details of what I know about Lower Glanny. The farm the Couch's rented from (Connor/O'Connor)was from a forefather of mine. The Couch family might have moved to NY using the family contacts of the O'Connor's, as this is where the grandsons ened up of Malachi O'Connor.
For a point of reference to what was happening in that region of Cork. Check out Tom Keneally's book 'the Great Shame' chapter 23. It has the stats. for the region of Glenlara (up the road abit).