I'm not sure what Thailand is accused of, or at least what some commentators here think it is accused of.
Normally when one country accuses another of 'currency manipulation' it means that the accused country has been artificially keeping the value of its currency DOWN, to increase its exports and decrease its imports (including from the accuser country). Yet most people here on TV think that Thailand deliberately keeps its currency too HIGH. Which, if true, would have the opposite effect: increase imports and decrease exports. In which case why would the Yanks be complaining?