I had a co-worker whose father was also into genealogy and her father was an Irish immigrant. Her family surname changed upon her father's arrival to America. The reasoning was because of a language issue as it was conveyed to me.

I strongly suggest that if you want to go further, to work with someone who is familiar with Irish ancestry, language, immigration and surnames. Only if you are for sure that this person is the first known immigrant in the line you are researching.

I don't think this is a brick wall necessarily, just a little bump in the road.

Best of luck!