The Seat enum uses zero indexed seat positions, however the auto seat heater endpoint appears to use a 1-indexed version of the seat positions. This has the result of the front left seat heater switch in HA throwing an error (unknown) and the front right switch controlling the front left seat.
A quick fix is to increment the seat index in remote_auto_seat_climate_request(). This works for my use case (using the fleet api directly) but I'm not confident it wouldn't cause an issue elsewhere