On Mavericks, how can I change the language of text in the new version of Pages? They seem to have removed such an option.
You can change the language of check spelling: http://help.apple.com/pages/mac/5.2/#/tanf3d8c3e49
You cannot change the language of the document (this concept is gone). I'm Brazilian and could only update the apps of Pages, Keynote and Numbers after changing my OS language from Portuguese (Brazilian) to English. I guess those apps are not ready for other languages as the time of this comment.