When you say “Site Feedback” are you referring to this forum or
I don’t think the current three main categories are sufficient but anything more you come up with will no doubt require maintenance by moderators.
There is already a post under this category that doesn’t appear to belong.
Does Discourse support sub-categories or will tags and search suffice? Just being able to search the forum is a huge improvement.

We’re referring to feedback on the Xert site itself. We’ll add more topics as necessary, and as more people start to use the forum. For now, the search feature is sufficient to help people find the topics they’re interested in.