When you have an article in english and switch to german language (even when the article has already been saved) a popup opens saying "Would you like to save the changes made to this language?". If you select "Ok" (just to be sure) you're sent to the english article again. If you select "cancel" (because you've saved manually before) the next popup opens, asking "Are you sure you want to switch the language view? Changes made to this language will not be saved.". Here you need to select "Ok", and the article switches to the german display.
When you save the article you're back in the english version again.
Publishing the article then seems to work, placing it on /web/guest gives the english content while /de/web/guest gives the german content.