Lol you're still making this harder than it is. Ok so they're not Americanized but they live in America and I assume one of them speaks English and are a human couple. So you can't buy them a bottle or a Bill Bellamy stand up DVD, but everything else is fair game.
You don't need to get all gimmicky because they're Asian
. Actually it'll be pretty funny if you came with a gag gift like a fancy set of chopsticks or driving for dummies book or something offensive.
But money is always a good choice. Every culture likes money.