Readarr sucks (not due to being a bad software... Don't get me wrong). Maybe due to how the media itself is messy, no good source like IMDb, messy releases that are hard to decypher.... Even worse for non English languages, let me tell you.
Also, cannot manage ebook+audiobook and you need two instances for just that.
I gave up using it as well.
Calibre seems better to manage, and to search&download you can always use prowlarr directly.