As far as I know, the headlights on the Euro5 versions only light up when the engine has started and the generator is supplying sufficient power. On the Euro4 versions, the headlights come on as soon as you turn the ignition key and remain on while the starter is turning. I have a Euro4 Interceptor and the information about the Euro5 comes from my workshop foreman.
So on the Euro5 there must be a trigger signal form the ECU to turn on headlights. The ECU ‘knows’ when the engine is running.
The new switches are most likely plug-n-play with the Euro5 versions but not Euro4 versions. There are probably wiring changes that let the right hand switch have the ‘hazard flasher’ feature work on the Euro5 as well.
Won’t know for sure until I can find a wiring diagram for a Euro5 bike.