Windows 8.1 Preview will come in several languages, but according to some leaked documents, in case users decide to install the update in a different language than the one already configured, the installer will remove all apps and settings.
Windows 8.1 Preview will be offered in Arabic, English, Chinese Simplified and Traditional, French, German, Japanese, Korean, Portuguese, Russian, Spanish, Swedish, and Turkish.
Installing Windows 8.1 Preview in a New Language Will Remove All Apps and Settings