It would be great if you could add a way to have the app find a different nzb when a snatched download fails. I've had numerous issues where when trying to backfil old seasons where the download will fail, but re-trying will just pull the same bad nzb over and over, but when I go out and look I can manually find a working one. Having a button that will search again but ignore the previous result would solve this.
(an app similar to sickbeard for movies, also coded in Python) has this feature already, so maybe you could swap code or gain insight from how he does it? He could probably benefit from your experience as well, since Sickbeard is a much more mature project than CouchPotato at this point.