The template parameters must be valid JSON or, if you are using a preprocessor like Twig, must evaluate to valid JASON. If I paste your twig code into twigfiddle.com I get output like:
"frage": "Vorname lautet Ryan",
"sql": "Vorname <> 'Ryan'",
"out": "1 Melissa Andrews
2 Miller Murphy
3 Aida Russell
4 George Smith
20 Ashton Wright"
If I submit that to the JSON validator at https://jsonlint.com/ I get told it's not valid JSON because of the newlines in the string value for the 'out' attribute.
The problem with your solution is that each \n in your Twig strings is converted to a single newline character so that the output JSON strings contain newline characters as above.
You probably need to write \\n instead of \n throughout your Twig code.
Note that if you are using the latest version of CodeRunner and wish to use a Twig preprocessor for the template parameters you need to explicitly select Twig from the dropdown menu. It is no longer the default.