It was possible to activate root and earned supersu.
Updated through the standard updater of the English-Chinese firmware to version MIUI-KHICNBH15.0.1
In the internal memory, there appeared (and maybe it was the xs before) folder downloaded_rom. Upgrade to version 15 was downloaded there.
Found on the Chinese site archive
http://pan.baidu.com/s/1hqpCPgCI placed this archive in the internal memory in the folder downloaded_rom. Through the standard updater pointed to the archive, updated, loaded - root became active.
Supersu also seemed to work - it turned out to update the binary file.
By the way, I also have update.zip archives, which I ignore on the bodies map. Recovery such as newsaxx (post # 19).