Your 'set lower column address' & 'set higher column address', should these variables not be preceded with the actual 'Set Column Address' command, 21h?
no , that is setting the offset of the actual display as it is overlaid into the memory map

Also, the 'Internal IREF Setting' command ($AD) , where in the datasheet is that command listed, I can find ample references to the Iref current & the calcs etc but can'f find the actual command.
its probably not a command at all but a data value that followed the contrast command that's become dislodged in space and time.