I'm putting a video that explain how this quest should work, plus the coordinates.
The ''Ancient Mechanism'' is that big construction in the middle of the area
The "Southern Hieroglyph" is the bird painting behind the lamp on the east wall, just north of the southeast corner (63.42,33.64)
The "Northern Hieroglyph" is the bird painting behind the lamp on the west wall, just south of the northwest corner (65,25)