Hi. Just in case it helps, here is a non-lawyer's understanding of how Japanese Wikipedia is doing.
Japanese Wikipedia is operating under the assumption that troubles happening there could be taken to a Japanese court, and judged under Japanese law. (Some troubles could be taken to an American court in some cases, and American law could be applied.) It is also operating under the assumption that administrators could be held liable if they knowingly not delete illegal material. The Foundation is relatively safe, I suppose, except in the case that it is directly involved in posting of some illegal contents (a case not easy to imagine), or knowingly ignore some legitimate legal complaint.
These assumptions are in my opinion widely held among Japanese Wikipedians, partly because discussion leading to the formation of these assumptions included people who were professionaly practicing law and studying law scholarly. There were discussions more than one time, regarding different cases. And if I understand it correctly, what you need to examine for your question is German law. Can German court take cases even when the servers and the official operating body of the project is in the U.S. ? Can German court apply German law ? Who can be held liable ? Answers are in German laws. Similarly, if you want to think about if some Wikipedian active on de.wikipedia could be sued in a Dutch court by another de.wikipedian living in the Neatherlands, I think you have to take a look at what Dutch law says.
Overall, no, increasing presense of chapters do not increase risks of Japanese Wikipedians. The "local liability" has been already there even without a chapter. Creating a chapter is, in a way, creating a contact address for those who want to make legal complaint or threat. So in that practical sense, the risk may increase. But then, if the Foundation has enough money, they may be able to ask for legal help more easily. That would make a local project stronger, being able to deal troubles that individual wikimedian cannot handle properly.
Now having servers everywhere is I think a different matter. That raises the question if people can bring lawsuit in those countries where servers are located. Maybe or maybe not. Again, it depends on the local laws.
On top of all these, if the party sued is the Foundation, then perhaps we should think about if the German court's orders can be executed in the U.S., something that is determined by the U.S. law, I think. Similarly, some of the U.S. court's decisions may be rejected by Japanese Court and a ja.wikipedian living in Japan may be protected from it.
==See also==
[[en:Private international law]] [[en:Choice of law]]
Cheers,
Tomos