The placement of the engines has nothing to do with metal fatigue from thousands of repeated 40,000 feet cruises with a pressurized cabin anyway; no German jet fighter was pressurized, so it's doubtful that they understood the technology either.

Also, the only Nazi aircraft of any type with root-integrated jet engines is the obscure Horton 229 prototype - and apart from that single cosmetic similarity, it has absolutely nothing in common with the de Havilland Comet.