Dear Long Nguyen,
Thanks a lot for the support. We have a website in German/English and work with WordPress and Cornerstone. For an unknown reason our homepage suddently wasn't connected with its English translation anymore. It's not a general problem because 4 other Cornerstone pages are still translated. If you click on the English flag, luckily the English texts are still there. But there's not way to get the connection back. When we clicked on the "Pages"-Button in WordPress (not sure what the translation into English is, but the Button where you see an overwiew of all cornerstone pages within the wordpress backend) the page is "in translation" as in being translated/under construction, but in the view where you see German on the left and English on the right the translated page is all German (as it is shown now on the website).