The only results I was able to find for human McDonald's were over the entire order, but that number was ~89% in the 2022 drive-thru survey. 95% at the ordering

The only results I was able to find for human McDonald's were over the entire order, but that number was ~89% in the 2022 drive-thru survey. 95% at the ordering stage seems like an acceptable (or even optimistic) target for initial automation. If it's still too low, you can make up most of the difference with expanded customer service during the demo period while you work on increasing accuracy.