Hi,
A parent search on the IGI, part of familysearch.org gives five children for this couple, all born in the Ballykelly area. In each case the mother's name is spelt McKANE. However I have found the marriage of a Robert Irwin to a Catherine McKEAN on 17 Jun 1862 in St. Canice Church of Ireland, Eglinton, Co. Londonderry. Eglinton is abour six miles from Ballykelly towards the city of Londonderry and both villages are much older than 1830. They were Built by the London Guilds who were given the land around them to plant in 1609. Ballykelly was built by the Fishmongers Company and Eglinton by the Grocers Company. Your date of 1830 probably refers to some of the more imposing buildings which stand today.
Regards