Hi, I'm from Germany and all my kindles are registered to my german account since 2011. Before I had my K3 3G registered on the Amazon.com account with German address and credit card (that is/was possible until the german store sold kindles).
Now the funny thing is when I click your link to go to the kindle highlights I see all my highlights (because I still have a registered US account but no kindle registered there!). AND the highlights are recent highlights up to today!
AND what is funny about it. This feature is not available in the Amazon.de, German account! But then does the NSA have my highlights as well?