You are correct but in my case the tracking was showing both letters were "in the system to destination" but it went days and never changed. I thought they were lost but my rural carrier said I should call them because she had delivered a certified letter and her posted transaction was never posted in the postal system.
I checked the postal tracking a couple of times after the inquiry board confirmed the receipt of my letters but still the tracking was showing the letters were in the system. Tracking showed the letters in Chicago for 6 days before I called the Judicial Inquiry Board. So, in my case, the tracking was useless.