The site onyx-boox.com is not an official site, it's only a site bought by a vendor ArtaTech (polish). They only sold some devices.
Booxtor works for the site
http://ereader-store.eu (German) and make the support of many users - read the forum.
Booxtor works closely with ONYX to develop the devices and the firmware.
Booxtor said that there is some flavors of devices, the firmware that he give is for the international market. So, you would prefer the firmwares for the international market, those given by Booxtor.