Peter,
Suggest you check on those vent lengths installed after the inspection. I think dryer max is 25' with 5 feet off for every 90 deg turn and half that for every 45. It is 28' from the dryer wall to the back of the house. You exit about 32" before that but all the angles and turns add in as well. I see 2-45's where it exits the house and there must be at least 2-90's back at the dryer end.
That cuts the total length allowed to 10 feet. We have a big lint screen in our dryer, 1-90 degree elbow and straight out to the outside flapper only 3 feet away, and still have to clean lint from the flapper about 4 times a year. Lint build up in dryer vents is a huge cause of house fires.
With all your insulation, do you need an outside fresh air source or a pressure balance inlet for the dryer and gas appliances, and cooktop vent? We talked about this months ago, but no installation has been mentioned.
Ron