Does the shadow ever go away after a scleral buckle?

Adaptation : If your retinal detachment was large & the repair involved considerable treatment over the torn areas, then there will be a visual defect (shadow) in your vision. Also, how long the retina was detached plays a role in how degenerate the tissues become. So hopefully your retinal surgery has been helpful and has stabilized your visual defect. Monitor your vision and very likely you'll adapt.

Yes: The shadow from a retinal detachment (RD) requiring a SB usually does resolve with time depending on how long the RD has been there & location of RD.