After a couple of years working with shell script and post-processing script, I’ve developed a web companion to Sonarr that manage your subtitles and download new one in desired languages (configurable by tv show).
You can have a look here: https://github.com/morpheus65535/bazarr
BTW, I do not accept donation and Bazarr will always be free. It’s my way of giving back to the community.
Have fun!