Now that I've been able to double check the schematics and the parts, I have found that my initial observation was correct. The only mistake I made was that there weren't any missing risers but rather a few missing steps.
Steps 1, 2, and 3 from Sheet 6 and Step 7 from Sheet 7 are all missing from the die cuts. It is not surprising to see why. Notice their position on the schematics. They were all located inside window punch outs, which do not exist because of the mullions. If your Chantilly dollhouse kit is not laser cut, you will not encounter this problem. This is a laser cut kit only issue.
I do not know how Greenleaf Dollhouses is handling this issue. They are most likely sending customers an extra sheet with steps so they can retrieve the missing ones from it until the die is fixed but I have found a quicker solution to this. Though you can make your own steps from wood strips of the same thickness and width, cut to the right length, you can spare yourself a trip to the craft store by simply using the scraps left over from Sheet 4. Mind you, Sheet 4 is the only sheet you will find a wood scrap of the right size, for this purpose.
If you turn Sheet 4 on it's side, you will find a scrap length of wood that is the right width as the steps. All you have to do is use one of the steps as a template for the right length and then cut your steps from it. You will need 4 of them and remember to mark them accordingly as Step 1, 2, 3 and 7. Use an Easy Cutter or a craft knife to cut through the wood and make sure your cuts are straight. Present them against the step template and sand down any jagged edges. Now you have the missing parts without delays or having to spend any money.
All the other parts are correct so there are no more missing items.
Since this is a laser cut dollhouse, there is almost no sanding required except in a few small areas where the parts were clinging to their sheets. You can use a fingernail file to sand these tiny spikes down.