Is https://github.com/box/box-windows-sdk-v2 the current SDK repo for Box V2 for Windows?
It seems the Java version is currently active, but that repo hasn't been updated in the last 5 months.
Maybe it didn't need update? ;)
I am not a representative of Box, but for sure I can say that this is officail and current SDK for .NET. It is listed on their site: https://developers.box.com/sdks/.
Development is not very active, but they accept issues and do merges of pull requests that people do)) (actually latest commit was 25 days ago)
I had some issue with SDK and try to spoke with their support. They accepted the issue, but the answer was (May 16):
I spoke with our developers and they have been just been heads down working on the new updates to the Windows Phone/8 apps that were just released. Now that they have gone live, they should have more time to make some of these bug fixes to the SDK. I still don't have a concrete ETA but will let you know as soon as I have a more concrete timeframe.