Changing the prompt file for the summarization step before rephrasing

I am working on a german Rasa Pro CALM project. I want my assistent to fully work in german. Therefore I already changed the prompts for rephrasing and the prompt for the SingleStepLLMCommandGenerator. But there is still one prompt sent to the LLM in english. It is the summarization prompt that summarizes the conversation ahead of the rephrasing.

Does anyone know how to change and rewrite this prompt? How can I implement a custom prompt template for the summarization?