For now CoachAccountable is only available in English. However, English speaking coaches have had success making CA work for their non-English speaking clients, because so much of the content that a client sees is whatever content the coach set up for them.
You can change email templates of CoachAccountable so clients will read your messages in the native tongue. And all of your Worksheets and Session Notes can be translated as well. You can also explain and translate to your clients some of the major things in CoachAccountable, like the Stream, Actions, and Metrics. Read more about this topic here.
And, for complete translation, you and your clients can translate the entire site using Google Chrome. Here's a step-by-step on how to set that up.