I am working on improving the community search results and I would like to know how the relevance criterion is calculated to sort the serach results. Is there anything that can be done to ensure that the relevant topics appear at the top of the search results list (tags, keywords)?
This documentation may helpful for you
I agree that Lithium can improve search as it no longer meets many community members expectations.
The good news is that improving search is on the roadmap for this year as per this presentation a fortnight ago - https://community.lithium.com/t5/Customer-Connection/Recap-What-to-Expect-2018-Lithium-Product-Roadmap/m-p/441727