What if Ireland had not been neutral during WW2?

The name of the state, in the English language, is "Ireland" and the associated adjective is "Irish", and both of these are used both officially and in common speech. And this usage conforms to the way we speak of all other countries when speaking in English. Indeed, it's the usage observed in the title of this thread. A thread about Irish neutrality in WW2 is not a context in which any confusion with the entire island of Ireland is likely to arise.

So I'm puzzled, frankly, as to why you prefer not to. The reasons you offer don't really account for it; other Irish people who live in Ireland and type on keyboards and value accuracy and etc, etc, use "Ireland" and "Irish".

I do note that using "Éire" when speaking English is something mainly done by British people, and ineed in particular by the kind of British people who think there might be some genuine question about whether independent Ireland has the legal or moral right to make and act on its own decisions about neutrality. So your decision to use it in this context might create - entirely inadvertently - altogether the wrong impression.