Improvements needed to Help Centre search

Please can some improvements be made to the Help Centre’s search functionality? Currently it isn’t really up to industry standard and is providing a poor user experience
• It doesn’t pick on synonyms/different terminology - so without keyword-stuffing (which is bad practice and poor UX), content gets missed. Already raised by someone else here, here and here a year ago and still an issue - especially when it comes to typos, Fin can detect these so the HC should be able to as well. Some typos appear to be accounted for but not all - we should be able to customise this.
• Similarly, if we have a standardised/approved way of spelling/styling a term, this is the only one we use within our content for consistency - however users might spell it differently. Their spelling is valid (and not a typo necessarily) but doesn’t match our brand-approved spelling, and so articles don’t surface for them. Eg. “multisite”, “multi-site”, “multi site” are all grammatically appropriate, but we only use the hyphenated one according to our brand guidelines - if a user searches “multisite”, the articles don’t show in the search results 
• There is no way to filter (eg. by topic, region) - much of our content is regionalised, but there’s no way to distinguish this without using the article descriptions which aren’t always visible in search results (as it previews the section where the keyword appears). Users have to open and check the description to know if it’s relevant, which is a huge time-waster. Users should be able to find which responses are relevant to them, just like Fin regionalises if you use audiences.
• Certain articles need to be visible in collections for visibility (and therefore can’t be “unlisted”) but are not applicable in searches, and are taking up space in those searches, stopping more relevant content coming to the top. For example our historic release notes currently live in the Help Centre for visibility, but entries from 2018 shouldn’t be surfaced in searches
Possible solutions
• Transparent keywords (as suggested here) to indicate topics covered in an article without needing to include in copy 
• Tags to achieve the same as above but also allow for filtering (eg. search only articles relevant to AU users, or only articles on a particular topic)
•  Toggle to exclude from searches (similar to the toggle to exclude from suggested articles) - would ensure they don’t clog up search results, without having to hide from the Help Centre