I have a lot more indexers than that, and not much better luck. You really need a private torrent tracker if you want to automate books. Every few years I look into a way to automate it more like movies & TV with just usenet and public trackers, but every few years I don't turn up much. I have Readarr running, but it rarely finds anything except the most mainstream bestseller type results. Just doing things manually with something like Anna's Archive or Libgen is really the only thing that works well. Results for comics work better, but I can't stand Mylarr's interface, so have always just manually done that too when I have the urge.
I have a lot more indexers than that, and not much better luck. You really need a private torrent tracker if you want to automate books. Every few years I look into a way to automate it more like movies & TV with just usenet and public trackers, but every few years I don't turn up much. I have Readarr running, but it rarely finds anything except the most mainstream bestseller type results. Just doing things manually with something like Anna's Archive or Libgen is really the only thing that works well. Results for comics work better, but I can't stand Mylarr's interface, so have always just manually done that too when I have the urge.