According to the manuals definition: "The hollow on the opposite side to the valve hole is an indicator for the amount of rim wear" you are saying it should be here as shown in pic. That was my interpretation as well. If that's the case sadly I believe I have worn these awesome rims out. If I would of done my home work sooner I would of put softer pads on. Shimano makes pads that are supposedly less aggressive on alum rims.

BIG BUMMER