i'm wondering whether it is possible to deactivate title streaming for several tracks or track groups (e.g. News elements, Jingles,...). Is there any way to do this with the built in encoder and title update function?
I don't think so.
The Now Playing plugin ( https://www.playitsoftware.com/Plugins/View/NowPlaying ) works well with an external encoder but the settings (which allow excluding track groups) don't work with the built in encoder.
I've used it with both Rocket Broadcaster (paid) and B.U.T.T. (free) and you might want to try that.
Both have advantages compared to the built in encoder in some circumstances. In particular the ability to use processing in the paid version of Rocket Broadcaster is good and B.U.T.T. has level adjustment and a useful meter.