When logging an upstart job with the standard
console log stanza, can the resulting log files in
/var/log/upstart be configured to be written with a mode or owner other than the default?
No, upstart runs as root, and is in charge of creating the log files. You'll want to do your own logging if you want to control the owners and permissions. You can just direct the output/stderr of all of the commands to a log file if that is what you want.