So at the moment there is no country that has claimed English as its official language for EU purposes, thus it's legally OK to ignore anything official from or within the EU that is in English.
Malta has the population of Oakland, but most of the people there apparently speak Maltese. Ireland has about half the population of the Bay Area but only about 40% of them claim to have some facility in Irish. In both countries it appears English is universally understood and spoken. (all this info from Wikipedia FWIW).
I think it would be smart for the EU to nominate an English (of some sort) as the supranational language as it would elevate no member state over another. This same approach has worked pretty well for India, where the use of that language has a far more fraught history. But Malta or Ireland could simply take one for the team and switch their nominated language.
I'm pretty sure that you can have more than one nominated language, given that Belgium and Spain have a bunch of them.
This is the reason the only Spanish language which is an official EU language is Castillian. The other three (Galician, Catalan and Basque) are not EU official languages. Same happens to many other languages spoken in Europe.
Maybe Austria would do it? It's the only EU country I can think of that doesn't claim to have its own language. Edit: also Belgium and Luxembourg.
https://www.europarl.europa.eu/doceo/document/E-8-2018-00402...