OP - I think there's only so much one can do to be as relevant as possible. After a certain stage, it's out of our hands, as there are things in the search algorithm we know nothing about/can't control.
I'm in a similar position, with a similar number of search results for bow tie as there are for button earring. I tag, title & describe to optimise for relevancy. My experience is that recency plays in to it by bumping a listing up a little, but after24 hours or so, it drops back to where it was.
What I'm finding is that the number of favourites I get, over all my items, seems to affect where I place...the more I get, the more relevant I become. I think that the number of sales a shop gets also boosts relevancy performance.
The best advice I got when starting was to not worry about being a sall fish in a big pond, but to be a big fish in a small pond. So I focused less on how I did in the general 'bow tie' search - when faced with over 20,000 results, buyers will start to do a more focused search...maybe they're after a purple bow tie, so they'll search for that. Or maybe it's a silk bow tie. Or an adjustable bow tie. So I make sure I cover all those more specific bases as best I can, so that I appear on the first couple of pages of those searches.
So for you, concentrate on how you perform for things such as your wooden button earrings and your purple button earrings etc etc.