Looking at the light in operation.
First the low beams. Oddly enough this headlight assembly includes a European Parking light in the headlight. And when you turn on the low beams for some reason it turns on the European Parking light as well. I can find no separate parking switch so far on the bike that would activate the parking light for an actual parking scenario.
The top of the H4 9003 bulb activates when the low beam is turned on. This hits the top reflector in the bulb which seems to be angling the light down to the road.
Switching to high beam this bulb keeps the low beam turned on, and keeps the European Parking light turned on, but this time it adds the LEDs from the bottom of the H4 9003 bulb.
These LEDs hit the lower reflector which is angled upwards shining the extra light above the ground splash of low beam light and further down the road.
EDIT: So the alignment tabs just keep numpties from putting the bulb in upside down and have the low beams turn on and hit the lower reflector and shining far down the road.