Beautiful mall. I’ve got two in my studio that I built soon after Savvy Seller was released. I’ll try to remember to post links and pictures when I get home and have access to my computer.
I found having multiple savvy seller registers on one lot led to a similar problem as schools. All the sims arriving for work in the building line up and enter one at a time so it’s best to have an opening time that is different from times when other lots have sims arriving for work or school. Mt solution though was to avoid hiring register attendants unless they were needed. Sims can buy from savvy seller shelves etc without a register.
Edit. Also the sims can buy anything on the lot that is on a savvy seller mat or shelf etc from all registers on the lot.