There are two aspects to language content in Tangerine: the application itself (user interface) and your instrument content (i.e. your reading assessment items and your survey questions/responses).
With respect to your instrument content, Tangerine can support and display any Unicode-compliant script. To date it has been used for assessments and surveys in more than 60 languages covering a wide variety of language families and character sets.
Regarding the Tangerine user interface, this refers to the system buttons that control the application, such as "Save Results" and "Next". The Tangerine user interface is currently available in English and French only.
However, if you would like to use Tangerine in another language please contact the Tangerine team. As Tangerine is open source software, you could contribute a translated version of the application's user interface, or you could arrange for this to be done by RTI International.