In my experience with dozens of Norway spruce, the interior browning is shade kill. My in-laws planted 50 Norway spruce ( a boy scout project run amok) to form a screen around the perimeter of the property forty years ago. The only trees with limited interior brown out are those standing alone in full sun. Five years ago, when taking over the property and after limbing up and removing invasive vines, we began annual deep root fertilization with Davey Tree. The trees rebounded somewhat but the interior shade out is still a problem.
I should think the chances of your spruce doing well are not enhanced by being under a maple. The problem is both shade and water competition. The Norway spruce on our property planted under the shade of Norway maples are brown dwarfs compared to those standing elsewhere. Perhaps the Norway maples are particularly bad but I find it difficult to grow much under their canopy. I’m on Cape Cod which is zone 6B -7.