Regarding the headline: why do Americans say "international" when they actually mean "not American"?
UPD: there is
Then you'll run into the new problem, that in context of kinda-international HN it will sound a bit off.
"International" - similarity to US / Western political systems and values, but not in the geographic boundaries of the US
"Foreign" - different from / opposed to (depending on how xenophobic whoever you're talking to is) US / Western political systems and values
So, in many ways mirroring the definitions. International is a thing in and of itself. Foreign is a relationship to something else.