Read the instructions inside of the Project.
This is a base project were is implemented an example of multilingual CMS using Wagtail 1.8.1. If the page doesn't have the content on the selected language, it will be choosen the English language(it's default, but you can change that).
If you wanna adapt this solution to your CMS, please see the urls.py for the configuration.
The select to change the language is on base.html. It's a Ajax function.
This is the final look:
!!Images will be upload later.!!