Protection against electrostatic paint by draining the charge
So it seems like placing a TVS in series with a suiatble high value resistor  across the CASE (Y) capacitor helps to leak this current out of the system. It also seems that I did not need to place this series combi across each Y Cap but only across the GND to CASE Y cap because all other terminals have some path to the GND (VCC and CAN lines via TVSs for example.)