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There is no international transit in the US. Every arriving international passenger must clear immigration and customs even if they connect/transfer to another international flight..
If CX tagged your bags to your final destinations, at the exit from the customs hall turn to the right and drop them off at the transfer desks. Otherwise, you'll have to take them to the Air Tahiti Nui check-in desks on the departure level.
You will have to clear TSA security before boarding your next flight.