Oh wow, I hadn't even thought of this.
For now, ST10.x doesn't support other languages than English. Due to the complete redesign of the interface, that mechanism couldn't be reused: it would only partially work, and we wanted to do things right. (Localization will be supported, just not yet.)
So what you're seeing is it partially working: we forgot that users that are loading ST settings from a previous version, the language setting in particular, will see the broken behaviour. What's worse, with no way to go back to English from within the app.
What you can do, is modify the settings .ini file manually.
Navigate to
Code:
%UserProfile%\stereo_tool.ini
and change the line that starts with
Code:
Language=
to
Code:
Language=Standard (English)