This is generally what tags are for, and tags have synonyms.
You could make the same argument about spelling errors – that a search for “guidence” should match “guidance”. It takes some very fancy search engine work for this to be possible, though. Right now we rely on the built in search capability of the Postgres database engine.
In reality, I think the best solution is curation – to have a staff member, or a TL4 user, edit in all the necessary terms to generate a good search match in the body or title of the post. And this is largely why TL2 users can edit the title and category of all posts – because the title and category (and tags) are so important to get right, we share that duty with as many trusted community members as we can!
It’s also OK to have several topics covering the same result, because human beings have the uncanny innate ability to describe the same topic with … totally different words, almost zero in common. I wrote about this years ago:
the TL;DR is
What we want is on the order of 4 or 5 similar-but-not-quite-the-same duplicates to cover all possible search terms and common permutations of the question. It is also OK for these duplicates to have their own answers so people who find them don’t have to click yet again to get to a good answer.