Paper does make a pretty good insulator and with ambient in the smoker just 29 degrees higher than the brisket, it could be the two things combined to keep it from getting above 196.
I've found most of the people eating my food seldom make critical comments. To some extent I think it's just them being polite, but I also think most people are used to rather boring home cooked food. The vast majority of people who prepare food do so because they have to, not because they like to. It's a chore to them and they just want to do an adequate job and be done with it. Most people who seriously take up BBQ, particularly those around these forums, are looking for the best quality they can turn out. It's just a whole other level of caring about the outcome. So the quality of what you're turning out is so vastly better than what most folks are used to eating at home they don't see the small shortcomings that you do. I'm always looking for the flaws in my food so I can try to avoid them the next time. I suppose years of having "process improvement" pounded into my head at work has rubbed off in other areas. Unless you invite over another BBQ enthusiast who understands you're looking for honest feedback you're unlikely to get much in the way of negative comments unless you really mess up. My dad was the toughest food critic I've ever had. He would complain about the tiniest flaws. No comment from him was high praise indeed.