As i see it is not possible to send yaml training data as json to the rasa rest api. It will handle the training data in the request as markdown. So it is not possible to migrate all training data to yaml when u use the rest api and send over as json. It is possible to send the training data as yaml string but there is no documentation how the string must be look like. The code tells me:
dict( domain=str(training_data), config=str(training_data), training_files=str(temp_dir), output=model_output_directory, force_training=request.args.get("force_training", False), )
but what is this training_files exactly?