I have screwed up and my flooring is about an inch off at the half way point between two rooms. I am gluing down engineered wood flooring on a slab and when I got to the room divider I discovered that it was off on the right side of the room. Is there ANYTHING I can do besides just eat it ???

Any advice appreciated.

Are you going to sand and finish the flooring? If it is unfinished and has square edges you can use a block plane to skin off the edge of each board where the groove is. Each row that you skim will help get back on track. You will only need to plane one end of the room and taper it off as you work from one end to the other. Its possible to take off almost an eighth of an inch and still have the boards fit together. An electric planer works, too.
If you are using pre-finished flooring you can still take some of the micro-bevel off, but very little. The tongue side will not be accessible to planing so where the boards join will look off balanced if just one side is planed.
Another way to correct the alignment is to leave micro gaps where you need to
"stretch" one side of the room.
A half inch would need to be worked on over a long distance, so you may be out of luck.

Really depends on the layout of the space if you'll be able to hide it. If your out at a doorway, you might be able to introduce a threshold piece which would let you continue the install square from that point, but would break up the continuous look of the floor. Consider other vertical terminations as well - I once had to re and re a unit once where the kitchen island wasn't in line with the seams of the floor due to the outer walls not being square. The Homeowner didn't care about being out at the walls but not being in line at the island drove him nuts so we redid the flooring to accommodate. So if you're out an inch but its along a wall where a couch or bed is going, then you might be OK.