What works is any intercity station to any other irrespective of location, so Thurles Connolly results in the correct fare, Thurles Sallins works, Thurles Skerries works too, any station within the short hop zone won't work
http://www.platform11.org/passenger_...res_matrix.php is the suburban matrix, imagine that with twice as many stations, single A-B is not the same as B-A at certain times
The spread of ticketing options is crazy the only practical way is a ryanair style pick your journey then get a quote