What do you have to observe in a traffic situation like this one?

Your answer is completely correct, and here is why:

In German traffic rules, when you face an obstruction like this cyclist ahead on a two-lane road, you are allowed to cross the center line to safely pass or overtake the obstruction (points 1 and 2). However, it is essential that you do not endanger other road users while doing so (point 3).

This means you should only cross the center line if the oncoming lane is clear and you have enough space to pass safely. If crossing the center line would put other vehicles or road users at risk, you must wait until it is safe. This rule ensures safe passing maneuvers while respecting traffic safety.

By following all three points, you balance the need to overtake with the fundamental principle of not endangering others on the road.