I’ve found that the AA website sometimes doesn’t correctly show flights that could be combined to make an award from Southeast Asia. Try looking separately for BKK-HKG and BKK-TYO and then for HKG-US and TYO-US. If you find flights, you can put them on hold using a multi-city search and then call AA to have them correct the miles required to what it should be as a single reward. If you’re comfortable waiting until close enough in, JL opens significant F and J award availability 14 days before departure.