You’re right that there isn’t such a feature in core. A workaround is to flag the topic to let the staff know, but that may take a while if the staff aren’t online all the time. Another workaround is to use Category Moderators.
A plugin will likely be able to do the trick here. [1]
After digging around a bit, I found this plugin that might suit your needs:
But note that there are some problems with it.
Maybe a Theme Component too? Let me take a look. ↩︎