> How will users from these countries react to an English, British or American flag?
I stopped reading right there because no one cares. If you have users that care then provide them with choices, just don't let them get stuck wandering around a page in Russian or Greek or whatever because you thought someone might be offended by a flag. Perhaps they're offended by crappy websites with no obvious way to change the language? I know I am, show me any flag from any part of the former British empire and let me get on with what I was doing.
> How will users from these countries react to an English, British or American flag?
I stopped reading right there because no one cares. If you have users that care then provide them with choices, just don't let them get stuck wandering around a page in Russian or Greek or whatever because you thought someone might be offended by a flag. Perhaps they're offended by crappy websites with no obvious way to change the language? I know I am, show me any flag from any part of the former British empire and let me get on with what I was doing.