Hi,
The HikaMarket trigger "onAfterVendorCreate" is called every time a new vendor is created (otherwise it's the trigger "onAfterVendorUpdate").
To get the HikaMarket trigger, you need to be sure that your plugin is right in the group "hikamarket".
Plugins do not have a "front-end" or "back-end" context, all "hikamarket" plugins are include when HikaMarket want to perform a trigger (for his plugins).
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.