As we all know, Ireland is predominately Protestant and has been through brutal conquest. What can be cone to make it both independent and Catholic majority. Bonus points if it still speaks English.
Only ways keep Ireland as Catholic are avoid English Conquest or then Henry VIII and his successor not bring England to Protetantism. Perhaps Brian Boru is succesful to unite Ireland so it can fight against England. I can't see way how it could become independent after English conquest. But on this case Ireland would speak Irish.