Hi Maria from Aussie,
I beleive it is now your Summer, we are now experiencing freezing Frost and Fog,
However the meaning of the term Seneschale is, The Chief Steward or Butler of a great Hosehold, sometimes the Seneschal had the job of dispensing Justice and was given High Military Commands.
The townlands you mentioned are not in Dublin, it seems your Ancester came from Northen Ireland, lucky you, they have all there records,
Townland-County-Barony-Civil Parish-Provence
Ballycastle-Antrim-Cary-Ramoan-Ulster
Ballycastle-Mayo-Tiranley-Doanfeeny-Connaght
Ballycastle-Down-Ards Lower-Groyarby-Ulster
Ballycastle-Londonderry-Keenaght-Aghanloo-Ulster
Ballycastle-Mayo-Tiranley-Doonfeeny-Connaght
Dunluce-Antrim-Lower Dunluce-Coleraine-Ulster
Oldstore-Antrim-Lower Massercene-Grannge of Mucamore-Ulster
All of the above is were you will find your Ancestor, I suggest you buy a Map of Ireland which is very detailed and get to know these Townlands, also visit the Pronti Website which covers all of Ulster and good luck, it seems you are on to a winner, if I can be of further help, just ask,
Regards Catherine