Mods on HN are people, and there's one person who posts publicly and responds to emails (dang). Moderator comments are not automated AFAICT, though they do lean heavily on standard language for all manner of self-evident reasons.
Mods also tend to get overwhelmed with busy threads and we've had a few particularly contentious ones in the past couple of days (middle-east conflicts).
Most HN moderation overall is accomplished through member votes and flags, and some automated tools to up- or down-rank submissions and automatically flag or kill submissions. There are a number of other factors at play, including the flamewar detector (<>>40437018 >, generally, posts with more comments than votes), and banned sites / userIDs. But none of those result in moderator comments to the thread.
If you have further questions, email mods with your concerns at hn@ycombinator.com. They're quite patient in explanations, which is how I know much of what I'm saying here, along with reading dang's mod comments, as I did when I found this thread.