I found the root cause of the problems of Tatort Navigation. And it has nothing to do with key mapping but it's because of one of my patches for HybridTvViewer. And my comment points to some possible problems and ...
// ignore uris starting with dvb://
// this works with HbbTV of ZDF. If there are some channels, which now have issues,
// further investigation must take place.
Now the situation arrises, where further investigation is needed. (Possibly for other channels also).