Did they make their case to the Vatican, who put them under English rule in the first place back in 1155, never mind authorized an invasion of Normans?
I mentioned on this thread that the 1916 proclamation states that “the right of the people to the ownership of Ireland and to the unfettered control of Irish destinies ... be sovereign and indefeasible”. Membership in the EU destroys both those rights; the Third Amendment directly states that EU regulations and directives must have “the force of law in the (Irish) State”; that destroys sovereignty, as does having a foreign currency (the euro).
I don’t think Ireland could care less what the Vatican thinks at this point. By your reckoning, does every member of the UN surrender its independence?