Is Ireland the only country to bring in two languages, Irish/Gaelic and English? Is English an official language of any other EU countries?
[0] https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:01...
Using flags alone is already poor UI since there are many languages which spill across the borders into multiple member states and non-member states, and some member states with multiple official and commonly spoken languages.
But a menu item that reads: [Irish flag] (English) like one that reads [Swedish flag] (Svenska) does not seem worse than the legacy use of the UK flag or the popular use of the US one.
PS: Gaelic is a more general term for Irish and Scottish. Ireland brings specifically Irish(Gaeilge in Irish) language.