I'm not sure how subtitles are going to make a difference, Temis. One assumes they'll replicate Tonto's dialogue, including his matter of speech.
How many people in Jakarta or Shanghai would know that a Native American character dropping his prepositions is racist?
As movies get more global, cultural niceties like that get lost. Only the broad strokes remain. For much of the world, all they know about Native Americans is what Hollywood has told them. There's your scary thought for the day.