About a week after submitting all of the requested data we received a letter that more information was required. Our marriage certificate did not have enough detail about where we were born, so we had to provide our birth certificates. I submitted that information and about a week later I received a letter saying I could order a copy of Muriel's birth certificate.
The birth certificate arrived about two days after I ordered it. It had incorrect data for our marriage date, so we had to send it back. We received a corrected copy about a week later. We could now focus on the other required documents (US Passport, US Report of Birth Abroad, Social Security Card, Swiss Residence Permit)