I really wonder why nobody asked for that yet and it is not included in the FAQ (yes, I've read it), but is it planned to translate only a part of an article?
I.e. I e.g. have an paragraph that I want to translate from an existing English article and thus add this paragraph to the existing German article, which does not have this paragraph yet?
Doing this manually (with proper attribution) is also a very hard (and somewhat technical) thing, so I would really like if a tool could help me here, but currently this does not seem to be possible with it, here.