First of all, a 2h correspondance between a flight and train is not advisable unless it's sold together as part of an itinerary.

I'm assuming you bought the super saver train ticket separately, and thus, if you miss the train due to flight or contrôle passeports or whatever, you lose the ticket and must buy another one.

Of course, you could be lucky, since DB is quite often late as well, with 4/10 long distance trains late statistically.