Based on the conversion factor you are seeing ~ -.02" WC with the door open and the baffle slid forward... that seems about right to me.
Also since it does change the right direction when you slide the baffle, I would suspect things are as they should be. It seems the smoke roll out issue may be helped by removing material from the baffle to open up flue.... but I wonder if that is going to mess up the operation of the stove. It seems based on the cleanliness of the baffle and pipe that something is working right.
I guess you can tell more by removing the baffle and operating for a bit to see how it behaves, I would suspect there is going to be a trade off.
Have fun with the science project.