What do you mean with fallback function? Per default Kiwix is in English, so if no localisation is matching the local language, Kiwix will be in English. But, if translation files are corrupted (what should never happen) and Kiwix does not start for this reason, there is no fallback. Kelson (talk) 16:42, 23 December 2011 (UTC)
Fallback means that if there is no translation for "de-formal" it will fall back to the translation to "de" and in case there is no "de" it will fall back to "en". Without fall back, missing translations for "de-formal" will immediately be shown in "en".
I guess Siebrand will be able to tell. Let's wait for his answer.
Kiwix will not if Kiwix doesn't have the code to fall back to other languages than English.
Oh, that's pretty cool. Do you have a reference to the fallback behaviour you can share?
The best I can share with you is: https://developer.mozilla.org/En/How_to_enable_locale_switching_in_a_XULRunner_application
... but this still does not answer exactly to your question. The best choice is: you check it out (by testing) yourself. If something goes wrong, please open a bug report at http://reportabug.kiwix.org Kelson (talk) 18:57, 27 December 2011 (UTC)