First: Xili-language compatibility is verified with WordPress 4.3 “Billie”.
Well known by donors, contributors, the functions related to the themes present in permalinks 201x-Xili child bundled themes are now included in the plugin itself.
It is therefore possible for all situations respecting the rules kernel (core) of WP to have permalinks integration with current language at the beginning of the URI instead ?lang = fr_fr at end of URI for example.
Note also that the language slug can be a shortcut to its ISO code but also an alias at your convenience associated with the activity of the website or its geography.
Possible to do tests with newest theme twenty sixteen (and his multilingual child theme).
Other fixes and code improvements continued to grow especially for parties of sometimes more than 5 years old. 😉
Note: for now, given the sophistication of settings, lack of filter, the approach php / javascript, the customizer is not active to create special navigation menus with insertion points (use page Appearance/Menus).
Thanks for your returns