Greetings, @action-chain.

My suggestion for your search engine is the inclusion of "wildcard characters" that allow more specific searches.

I assume you use post tags as keys for "topic tracking".
The weakness of your system occurs when the user needs to combine several tags to make a search.
For instance:
Venezuela + Dentistry
topicX = Venezuela
topicY = Dentistry

The result obtained shows the result of applying the logic gate "OR", instead of using "AND".

Namely:
topicX.OR.topicY
when actually it should show the results for:
topicX.AND.topicY

It is an easy weakness to correct. You could implement characters that function as "Joker" and allow the logic gates to be symbolized. "AND" is generally represented by the "+" character, while " " (White space) is used to represent "OR".

I hope I was able to explain my point clearly, and help you in some way.