Mooncoin itself is about 25 miles south of (the town of) Kilkenny. Mooncoin is in County Kilkenny, on the River Suir about ½ way between Waterford and Carrick-on-Suir. It is only about 8-10 miles north-west of Waterford, where the Waterford Crystal used to be made.
Look at my postings of April 10 on this forum to get more sources of Irish info on the Internet. If you have not visited Ireland, you should plan on doing so. Give yourself a year or two, to gather information first. You will save yourself time that way by knowing just where to direct your search.