I am a corporate and IP lawyer in Israel and I represented Israeli and US companies that had businesses all over the world including in places like Croatia, Germany, India etc.
I cannot answer questions with respect to the laws of the US or Germany, but I can tell you what we did in my firm in similar cases:
The most common solution is to find a third country that will be "equally bad" for litigation for both parties, usually we picked the UK.
Another solution is to say that if the German side is suing, it must do it in the US and vise versa - if the American company is suing, it must do it in Germany.
You can also determine that no courts will be involved and you will settle all disputes in an arbitration. There are a lot of options here, you just need to be creative.
If you have followup questions, please give me a call and I will be happy to help in the limitations mentioned above.