>> currently that average interest rate is below 3 percent [1], so for any countries with >3% economic growth, it really doesn't matter - they'll be able to make their interest payments to one another

What does 3% economic growth mean? Is it measured in terms of that country's own currency? But isn't that currency's value inversely proportional to the amount of money which was borrowed from the Fed? So the higher the interest rate is, the more new money the government has to borrow from the Fed in order to pay back its old debt, the less the currency becomes worth, the less meaningful this 'economic growth' percentage becomes (because that growth is measured in this fast-deflating currency). This seems to be mind-numbingly complex.