The number 1 rule of European (esp. German) train travel is - minimize changes as much as possible. Timetables are so unreliable that booking a long trip with a change is just too much risk.
In the other direction on the other hand…
The DB Navigator app can now "even" show that your you are no longer bound to specific trains when that happens, with a little banner in the top.
Then you get the pleasure of arguing with DB about compensation. Of course, only possible by post.