How to protect bistable latching 2 coil relay with diodes?
A reverse diode does not really protect the relay coil - it protects the rest of the circuit when the relay coil open circuits and the magnetic flux collapses producing a peak voltage that can be many hundreds of volts. If it has two coils then 2 diodes are probably enough. If it has one coil this usually means that reverse voltages may be needed to de-latch it and a slightly more sophisticated circuit is needed - see "Bistable coils - operation" on data sheet front page.