A couple of thoughts on that picture:
Comparing with what little I can see in the TIE cockpit ceiling, the subassembly here on the Y-Wing looks to have been cut down a bit to fit the hull. Relative to this view, the height (vertical axis in picture) appears to be unaffected. However, the width (horizontal axis) is trimmed a bit. That's OK, because the vertical axis corresponds to the width of the ceiling panel in the TIE.
Oddly, the modifications seen in the grayscale picture above do not seem to have been present in the colour photo. These were done sometime after the colour photo was taken.
Having seen this close-up, I'll buy that the base plate of the sub-assembly was scratch-built with little chipping details added. However, the bent pipe thing on it is harder to make out. Looks like it could be a tool from an armor kit or a bit of landing gear. Hard to say.