Hi Arthur,
While the not-editable content is in English only, we do allow for all reseller to add their own paragraph in the footer or header in what ever language they would like. We do this because of ICANN's policy, and really the main reason why we do this is for auditing reasons. ICANN requests us to send those messages in the language of our registration agreement with the registrant this is in English, so we are required by our contract to send those messages in English.
-Amrinder