There are lots of ways to drop 24 volts to 12, but before you think about those, have you tried contacting the Factory in China about this? They might have a web site.
If you can't get any cooperation, contact the Chinese embassy for the phone number of their trade people. I imagine they'd love to hear from you.
In the life of the scooter, you may need more lamp bulbs, so it would be worth getting 3 or 4 now if you have the chance.
If you really, really can't get another lamp, you could look at the battery and see if there is an accessible 12 volt output on it.
However this will mean you also have to know what else runs off the headlight switch. Probably the tail lights also get this same voltage, so they would have to be 12 volt ones as well. Also, the indicator lights and the indicator flash unit.
You could put two headlight lamps in series, I guess, but they can't both be at the focal point of the headlight reflector.
Did you buy it from a local agent or did you get it sent from China?
If there was an agent, it is their problem.
If it was brought in directly, do you know the procedure for getting it licensed?
It could cost thousands if the licensing people have never seen one before.
Sounds like a fun scooter, though.
Is 200 watts enough? How fast can it go?