Two film posters hang behind Alan Esslemont’s head; Rocky Ros Muc, a 2017 documentary on the life of pugilist Seán Mannion and Arracht, the acclaimed survivalist thriller set during the Great Famine.  Taken together, they tell a story of how Esslemont, a Scottish native and director general of TG4, is courting something different for the Irish language: Laying a pathway for film to earn status for the native tongue and, in doing so, pursuing greater purpose for TG4 as a public service broadcaster. Esslemont, who has held the top job in TG4 since 2016, sees a far greater responsibility in…