as I've found that the previous search system worked well for my intended use of it
There was a cutoff before. I do not understand how this could have worked for you before.
Maybe try switching to physical games, as some of those are released there and some in "other" and some in (computer) games. And if there is no common tag used by these projects, a internet search with site:itch.io topic-of-interest will be better. Itch's search is still optimised for title search. So the projects would have to include your topic in title.