Hello, I am unsure if this can help answer your question in any way, but it is multilanguages related, so I thought I could share it, anyway : https://forum.xwiki.org/t/xwiki-in-2-languages-with-a-left-panel-selector/ (it still works fine at xwiki.linuxvillage.org, for 2 languages, with XWiki 18.5)