Why do you think that is?
Asian Americans are so successful that they certainly must not have disproportionately higher rates of suicide right? That might be a sign of some "impairment" going unaddressed! Or maybe you see the rate at which they're killing themselves as yet another metric of success? Those scrappy East Asians are just so good at doing stuff!
They outperform by the metrics that matter for a clinical diagnosis and the West is so quick to jump to the conclusion that they're "under diagnosed", it's a uniquely Western and especially American conclusion.