I noticed that you still cannot use the wide angle lens with the Structure SDK 0.8 . With the wide angle lens attached the scanning is not getting the scale of objects like chairs correct. I see the same issue in latest version of the Structure App (from the App Store). Note that the Canvas app and the Calibrator App (also the latest from App Store) are correctly getting the scale of objects like furniture correct with the wide angle lens attached. I can share photos of the scaling issue if needed.
I am using Unity 2017.3.1f1, iOS 11.4 and xCode 9.3 and using an iPad Air 2.