Currently Insight supports 4 languages - English, Japanese, Korean & Spanish. In the near future all the 18 languages supported by TableCheck will be supported by Insight as well.
The default language is one of the four if the default browser language is one of the four, for any other browser language the default Insight language is English.
In order to change the language, click the globe icon on the upper right of the top bar & select the desired language.