This forum software, as has so often been noted, sucks. There is apparently some technical reason why CW cannot update it, although explanations have been vague. Whatever the reason, it's probably best to assume that software solutions are not an option.
That leaves only the human solution: volunteer moderators. I know that the software supports a permissions system whereby designated users may move and close threads. That's all that's needed. Create a quarantine folder and give a few users the ability to move threads there. Forum administrators would still decide which threads to delete and which users to ban, so there's little chance a volunteer mod could accidentally or maliciously censor legitimate threads.
Volunteers' email addresses could optionally be added to the notification list when a post is flagged by another user. This, too, is a feature already supported by the forum software.
This is not a radical concept. It's been done that way for many years on KVR, and that's a very well-moderated forum despite the fact that it routinely attracts a lot of, er, "the wrong crowd". The "I got da Waves Mercury bundle so I can make my beatz but I can't get it to install" posters get run off pretty quick. And I've never seen a "buy genuine Nike shoes direct from China" post.