Hi mayaa! I cropped and enlarged the area of the green box, the one you point to a carved stone treasure marker in the middle of it. I checked around and inside the black line which has the right green box.
There might be treasure where the orange line connects the white square with the purple box above it.
White in general is a color indicator, I use for natural caves or man made tunnel entrances and other similar type excavations (including tombs). Purple line box for paranormal type sites, including tombs, ancient religious artifacts, temples, spirits, and burial grounds. Orange markings or line box for deeper man made gold objects.
Red line box or solid red circles, is for very deep coins/treasure or artifacts of value. Green line boxes in general for various other targets, mostly archaeological such as old ruins or foundations but especially non-metallic objects like flint arrowheads, bottles, pottery, and carved stone markers.