How to retrieve error messages in English for Applicant API

Hello Personio team!

During testing the API for passing applications to Personio I discovered that error messages are returned in German.

Example:

{
    "success": false,
    "error": {
        "code": 0,
        "message": "The given data was invalid.",
        "errors": {
            "last_name": [
                "Bitte geben Sie last name ein, um fortzufahren."
            ],
            "email": [
                "Bitte geben Sie email ein, um fortzufahren."
            ]
        }
    }
}

Is there a way to return them in English?

I tried:

adding Accept-Language header to "en", "en-US" and "en-US,en"
adding a language parameter to the URL -> https://api.personio.de/recruiting/applicant?language=en

None of these work. Can you please help?