All we need is probably a custom recovery and a unlocked Bootloader to flash the zip file. I also wrote several EMail to Vivo global but I get an automated Answer everytime, probably sending an EMail to vivo in china would be more helpful maybe. I'm also out of ideas.
The only thing I did, is compared both Installer-scripts from the global and china Firmware. The script checks first the modelnumber which is, of course different. Maybe changing the Installer-script modelnumber of the global Firmware to the china modelnumber could be the key.