I bought a Euro left hand switch from Japan when I was ordering some side panels so the shipping was gratis. The switch cost me about $130 US at the time.
It is not 100% plug and play. I plugged it in and everything works except the flash to pass as there is a white/yellow wire in the connector that does not exist in the US connector (center of top row shown in pics). This space is empty on both sides of the connector in the US bike.
Without both diagrams not sure what it would take to wire from the back end. The white/yellow wire goes back to the flash to pass button on the handswitch. Perhaps there is a separate activation circuit with a diode or something because it is physically possible to activate the high beam switch and trigger the flash to pass button simultaneously.
I'm heading out for a 7k mile trip in 2 weeks so it will have to be a project for another day for me but seems like it is doable if one knows how the euro bikes energize the high beam shutter from the F2P button.
Hope this helps.
Andy