The MAX14783E is designed to withstand ±35kV ESD HBM, but surge protection at 2kV/4kV levels requires additional protection on the bus lines.
Customers will need to add external protection to be able to pass surge testing. At a minimum, this typically includes a TVS diode on each line and a carbon composite or thick-film resistors between the TVS and the receiver inputs (A and B). Depending on what the customer is trying to meet (surge level, surge duration, etc), the SM712 and a some 10ohm/0.2W resistors would be a good place to start.
If the SM712 cannot meet the requirements, then they either need to add further protection (maybe something like the TBU-CA0065-200-WH in the line before the TVS diodes and a varistor to ground on each line – like the MOV-14D561KTR).