If I put multilang text in the Description of a Choice activity, it shows the full text with multilang tags rather than filtering it. For example I see:
<span lang="en" class="multilang">Join your group!</span><span lang="si" class="multilang">ඔබෙ...

The Choice name field behaves as expected. i.e. the name changes with the selected language.

Moodle 2.7.8+ (Build: 20150521)