When an activity Choice is created using the filter multilang, not all the activity is shown consistently in the appropriate language. The activity description before selecting the activity is shown fine, but when the user selects the activity (I mean, once inside the choice activity), both the description as well as the choices are shown with the involving languages concatenated instead the appropriate language.
Using the "inspect element" of the browser let know that the multilang tags were ignored by the multilang filter.