xili-language version 2.15.2 is a technical updating for WordPress 4.0 (remains compatible with previous version) (constant WPLANG is now obsolete).
This site itself was used also as test before and after 4.0 update.
Another tests were done on empty websites and with importing of xml file from other multilingual sites powered by xili-language.
Soon a post with a step by step process to export / import xml datas that need some “attention” !
Thanks for your return !