Just a note that log timestamps (the ones starting each log line) are always in Z/UTC, but many timestamps reported in the log line text are displayed in configured local time. As can be seen in the final image above, the Engine's master tick also periodically logs what it believes local time to be. The time displayed in the header of the UI is the local time of the browser, not the host system or Reactor, and so may still be different (i.e. you're sitting on a browser in California at UTC-8 working on your Pi in New York at UTC-5).
I will bind /etc/localtime to future docker containers. Not possible since it's a security risk, which makes sense (you don't want containers being able to arbitrarily mount things anywhere in the filesystem). So, looks like a TZ environment variable is where we'll be. I'll add it to the docs.