If the assignment shows up in French that most likely has to do with your browser settings. Make sure you are set with English as your language. If you are using a browser other than Chrome or Firefox, it would also be worth trying one of those.
The message about not finding schemas also suggests that perhaps you have made big changes to your notebook. E.g. downloading it and running in on Colab and then reuploading it to the Coursera website is a disaster. Colab modifies the JSON source in a way that is not compatible with Coursera. Please do not do that.
If you want to try getting a fresh copy of the notebook, here are the instructions for doing that.