How to access response variables in intent response?

Configuration
1

the problem is best shown by the following example

  - action: python_script.myscript
      response_variable: pythonresult
    - stop: ""
      response_variable: pythonresult
  speech:
    text: "Test result of the Python script: {{action_response['myvariable']}}"

This works just fine. But to support other languages the correct way would be to replace “speech: text”, by 'response: "default"’ and put the text in the responses file

    - action: python_script.myscript
      response_variable: pythonresult
    - stop: ""
      response_variable: pythonresult
  response: "default"

with the response file:

responses:
  intents:
    MyIntent:
        default: "Test result of the Python script: {{action_response['myvariable']}}"

But this fails with “UndefinedError: ‘action_response’ is undefined”.
So my question: how can I get data from a response variable into the “response” part?

Thanks in advance
Horst