I too am searching for Keanes who were from Castleisland, although I also heard my mother mention Knocknagoshel.
My great grandmother was Ellen Keane born c. 1852. Her mother's name may have been Rose Ellen. Her siblings were Daniel S., Julia (who may have married a Healy), Hannah, and Kate.
Ellen married my great grandfather Maurice O'Connor and had the following children: Daniel, Hugh, Simon, Jack, Catherine (my grandmother, b. 1876, who married Cornelius O'Leary), Minnie (Mary), b. 1878, and Ellen (Nellie) b. 1879