- Plesk for Linux
Non-English language, e.g. Russian, is selected in the Administrator's interface language field at the Plesk > Profiles & Preferences > Administrator's interface language page.
Some interface objects at the Plesk > Extensions > My Extensions > Watchdog > Open > Preferences tab page stays in English.
This is the Plesk bug #PPPM-9971 which will be fixed in future product updates.
Currently, there is no workaround available.