Any pop-ups, messages, etc., should be in the language selected by the last user. For example:
One of our Dutch users had a time out message, but the message appeared in English.
Absorb's response was:
While it is true that the user's default language is Dutch. The default language of the Learner's Experience page is English. When the timeout message happens, the user is effectively signed out of the website. This means that the website's default language (English) will override the user's set default language (Dutch).
In this case, since the user selected “Keep me logged in,” selected Dutch as his home language, and chose Dutch as the home language in the lower left corner, the message should appear in Dutch. Our Finnish users reported the same issue.