^I suspect some still think the US domestic take is more important than the International take. The question is do the studios think one is more important than the other? Sure any take at the International Box office is subject to exchange rates.
The last few years have shown that these sorts of "blockbusters" are definitely trying harder to appeal to international audiences, which would indicate that international box office is pretty important these days. That's why I doubt the aforementioned "15%" number is still that applicable for big-budget extraveganzas, and assume that more favorable to the studio agreements have been made for territories where high revenue numbers are expected (it may still apply for something like a low-budget comedy where the international is still somewhat of an afterthought, and obtaining the best deal isn't worth much effort).
Exchange rates have to be considered for shareholder reporting purposes, but most likely a lot of that cash is never repatriated to avoid paying US taxes on it.
Agreed, I think the 15% is too low esp. for the tent pole releases, sure as you say it might apply for some releases. But surely the studios are in the stronger negotiating position when it comes to these tent pole releases. After all if they went to a cinema chain and said we want 40% of the box office take it or leave it, If they leave it they don't earn any revenue from it. After all the punter will go to which ever chain is showing it.