Yes, this was in fact an advanced screening, albeit not one for a very exclusive crowd I'm afraid... Cinema listings for cities like Basel, Berne or Zurich are refering to the language of this Film as being "CH-D" - Swiss German, without any indication concerning subtitles. Didn't find any information on screenings in the French speaking parts of CH at all. Even if your Swiss German is not 100% fluent I'd give this film a try. As you are most probably rather well informed about the background of the whole story, you may nevertheless grasp the important points, I'm sure.
(And one small goodie (or even a laugh...) for native English-speakers might be Jackie Fouse's rather cute English accent when trying to speak German)