Dave,
The same logs include both backend and frontend instance logging- they are
not separated. You could be experiencing a delay before long-running
backend log writes get flushed.
You might be interested in the LogService API,
The docs for downloading logs make no specific mention of backends,
and from my attempts it seems that you can only download logs for your
frontend. That would be strange though, and to make matters worse a
web search for google app engine download backend logs (no quotes
obvs.) reveals nothing
