The spruce braces are being prepared and rough layout on the back.
X-braces will add some needed stiffness. It shows the character of the top more.
The centreseam is reinforce with cross-grained spruce called a back graft. It it now being glued.
The back graft is processed to its height...
...and rounded contour. Sanded down to #240 grit garnet sandpaper.