full text search, when given a query like "reise priebus" which has zero results will rewrite the query to use the provided suggestion, "reese priests". This isn't really a good fix, but it is a feature we have in production and relevancyLab should do the same.
it's a bit late so i havn't looked, but might only need turning the feature on in the SearchEngine features? We might need a higher level ticket, to verify relevancyLab is running queries the same way as production. There might be other flags we havn't set properly.
We definitely want the basic search to be the same in the no-longer-a-lab (T128765) and in production, but I'm not sure about some of the special hacks that are there to improve the user's experience, like auto-running a suggested query, or searching another wiki (different project or different language). Are we tuning the user experience or the search engine results in the no-longer-a-lab? Could be either, I guess, depending on what you are working on, and what you consider search results and what's UX.
Please enjoy this maximally wishy-washy comment! We definitely need to understand what's going on, though.