There must be thousands of forums and they look and feel very similar but the hardest part is moderation which we never see and I imagine everyone implemented differently.

I just had a fun thought. Rather than permanently collapsing a comment when it reached some level of undesirable it can be a % of the time where the % increases with activity and the number of replies. Even if you can detect great comments they normally drown out other candidates. If the topic is active enough unfolding those 30% of the time is enough visibility.

Try make it more like objective a-b testing where things are compared on a level playing field.

New posts should sort to the top in a sub forum but (like hn) it isn't required to only have new posts there, highly rated slightly older things may mix in but (to a lesser degree) older and less popular topics can also be mixed in. If no one looked at it we don't know if it is any good, it might be just what the project needed.

If the judgement isn't as final ai can also assist with ratings.