[pkscout]

Is it possible that the addon change the audio profile on-the-fly? The problem: when i watch live-tv the tv channels sometimes switch to stereo (e.g. in commercials) and after that to 5.1 again

No, it's not. The addon is listening for changes in the Kodi state (start playing, stop playing, etc). It is not capable of monitoring the video/audio stream for changes in state.  Unless you have done something unusual or have some very strange equipment, your AV gear should be capable of handling a change from stereo to 5.1 during playback.