It will be very useful to show a user some similar topics that already exist not only in the same forum but across all forums. This way, content duplication can be avoided and it can enrich the user experience. Does such a feature already exist in wpforo?
Not relevent to your question, but you should fix all those crashes and errors in your pages.
The next version includes topic suggestion while user writes the new topic title.
You can also check wpForo 2.0: https://wpforo.com/community/wpforo-beta-testing/wpforo-v2-0-0-4-testing/