If the emulsion were to “wash off”, you would see definite changes to the thickness and likely the termination line would show some folding of the emulsion. Because the leader is black meaning it developed properly along with several other frames, most likely, the damage is do to improper loading of the film on the reel.

Additionally, the edge printing is placed on the film using light. In other words, this printing is exposed film that develops up just like a camera exposed image. Examine the film in detail using a magnifier. Examine the film by transmitted light (looking through the film) and by reflected light. You do this by holding the near a lamp and twist the film, looking at its surface. If the emulsion has been stripped off, you will see differences in the coating thickness seen by reflected light from its surface.

A hardener works on the gelatin that is the binder for the light sensitive goodies (salts of silver). A hardener changes the infusion rate (time it takes for the developer which is mainly water to percolate into the emulsion structure. Thus, a hardener will retard the developing action. This is critical if the developing time is short, just a few minutes. If the developing time is over 5 minutes, likely you will see no applicable effect from using a hardener. Generally, a hardener is used when films are not pre-hardened and in hot weather processing. Likely not applicable in this case.

I would develop another test roll. This time double check reel loading. I won’t hurt to make a test roll using fresh film. Reel loading can be daunting.

P.S. Your film from 2008 is not that old, it should be OK!