Hey @jmeler 
If I’m following correctly, I think one answer could be a partially restricted “General” category. You can set the category restrictions such that all users can see and reply, but only staff (or a designated group of your choosing) can create new topics. This should avoid any opportunity for categorization chaos. Take a look at How to use category security settings to create private categories for more information.
Another optional tool if you expect a lot the generalized content to be user-submitted is to set the “General” category up so that all new topics must be approved by staff. This way you would have a filtering system.
You may also want to investigate the usefulness of Discourse-docs: Documentation Management Plugin. You would need to teach your users of its existence, but it could be a good way to organize everything.
I don’t expect mirrored topics to be on the roadmap any time soon, so I’m hopeful one of the above solutions will end up being a workable alternative! Let me know if you have questions.