That is great that you were approved for expedited processing. Congratulation! DOS told me that they will finish my application way before my J1 will expire and for that reason there is no need for expedited processing (my J1 expires on April 2021). Can I just ask you when your J1 expires?
Regarding the email which you received, there is a possibility that they messed up something and gave you the wrong information and all your documents were receiver but I would rather sent them all what they requested to make the whole process faster for you. Maybe add in the email screenshot of your timeline from the DOS website and ask them what is going on with your application.
