Why the translation only work from English to other languages? How can a speaker of one of the translated languages add a section to the page directly in its language and it marks the English version that need to be translated. The Extension should work in all directions. And we should be able to directly edit all languages' pages.
Topic on Help talk:Extension:Translate
When I try to edit a translated page it says "This page cannot be updated manually. This page is a translation of page Wikimedia Indigenous Languages and the translation can be updated using the translation tool." (on Meta), but a contributor cannot use the translation tool to add "new stuff" or a new section to the page, only to translate sections of the English page.
That is a more complex problem. See this presentation at Wikimania about one system that does that.