According to CASB, the Swissair flight was due to plain overloading of wiring - even if your Pax entertainment only uses quarter of an amp at 28V per seat get 200 using it (plus the PA muzak) and you've got welding current looking for somewhere to go.
There is no comparison between light and commercial aircraft as far as wiring and shielding practises are concerned. Most modern transports have survived HIRF testing with fields of 50V/m or even 100V/m - much higher than any radar field.
All our aircraft are test vehicles with lots of extra instrumentation wiring but the only effect we've had when getting too near the "1 million watts" weather radar on the field is a jump in the Radio Altimeter which happens to be on the same frequency. This happened so regularly during storm season that my nickname was "NEXRAD".