I usually always tell the server before I tap that I want to pay in EUR. If I dont know (enough) of the local language, then I just repeatedly say "Euros euros euros euros" when the screen prompts a "Yes/No" selection.Last night SYD+1 got caught be a “helpful” staff member. Although, the machine wanted a signature. Thinking about it afterwards, there might have been an option to “Cancel” (and tap again).
Anyway, at new places I’m going to say immediately on tapping, “Wait. I want to pay in Euros” (and I’ll be saying that in Spanish).
