How to compensate for a height difference of 13 cm over 6 meters to the neighbor?

Your neighbor should create infiltration options on the way of his water to you: extensively through a permeability-friendly surface, as a barrier with drainage before the boundary, or as any combination thereof. Many will be jealous of you here because you only have a question and not a problem ;-)

However, these 17cm go up from us and not as a slope downwards. And that's not so great, right?

Yes, of course it would be smarter if the water didn't run down towards you. On the other hand, it wouldn't be so bad if you had the lowest point at the end of the terrace. In the Munich area, the soil apparently absorbs water quite well. I would therefore focus on the question of what you want. With such a small distance, I would try not to always see the neighbor directly. So, for example, a hedge on a 30cm mound, which would then also hold the water on their side.

Thank you An earthen embankment is definitely a solid solution, I agree with you. Plus, a nicely planted strip at the front looks a bit like it is our raised bed. The strip probably isn't very important to the neighbor anyway, since his garden on the other side of the house is huge. Why does no one like L-shaped stones?

Because that would be shooting sparrows with cannons at that point?

The metaphor is an understatement. That would be an ICBM against a flea.

L-shaped stones are used to catch slopes. What you have there is not even a slope. That's not even a step, it's a slightly higher threshold.

There will surely be a fence there. You then put a lawn edging underneath and that's that.

What does the neighbor intend to do about the enclosure?