I have the same problem, although even without tokens enabled.
here is a small part of the survey, if you wish to test it:
platformetest.limequery.com/68632/lang-fr
There are 3 languages (FR, DE, EN),
no tokens,
Q by Q format,
version 1.90+ (hosted by limeservice)
If you try to change to say German, it works for the 1st question, ie you re bounced back to the start page and can proceed in the requested language.
However if you want to switch language afterwards, the question that was displayed when you changed it is going to be translated, then clicking next you get mixed languages. The question is in the "default language", but the language menu is in the language you asked for.
Also in a longer version of the survey, when changing in the middle of a group of question, sometimes you get back to the description screen, then back to the question you were at when language change was made....
Any suggestion welcomed!
Thanks,
Luge
I should add: there was no such problems with the 1.87(8338) version.
@vgournay: have reported the problem to the bug tracker? Can't find it, what's the name you gave it?