It would be nice if I could assign different proxy settings for each of my categories. For example, this way I could use my normal connection for private torrents and my proxy for public ones.
Thanks for your time.

If some spy enters a private tracker to log users or the administrators are coerced to share the database: they'll get you. It is a false sense of security. The solution: only share legal stuff or property you're authorized to, as required by Tixati's user agreement.
This setting does not make sense imho. Use different clients or a sandbox to launch multiple instances of Tixati.