Would it ever be reasonable for you to add a few other sites that the game searches for images. Sankaku Complex and Danbooru might allow the game to get a more thorough image set.
Viewing post in Waifu Solitaire - Lewd Edition jam comments
That's a good idea but there are some issues that prevent it from being practical. Danbooru and Sankaku Complex have a limit to the number of tags you can use at once (2 and 4, respectively). It takes more than that just to weed out unsuitable file formats, sort by popularity, etc. Even if that were solved, there'd still be the issue of duplicates, which is a solvable problem but would take quite a bit more effort than I'd like to invest at this point as I'm not really actively developing the project anymore. Sorry orz.