To me, abradable coating means a coating that will wear or abrade to take on a tight seal for the rotor tip to housing clearance. Whereas the older Gen3 SC coating would chip cause it wasn't as abradable. The chips would begin the disbonding of the coating to the rotor.
From the looks of the coating I lost on my Gen3 rotors was indicative of disbonding and not wear or abrasion. The coating was removed progressively but scalloped like it came off starting in one location, in large irregular chunks.
I believe that the differential expansion and clearances between the rotor and the housing since brand new, chipped the two rotors that had 2/3 coating removed.
The methanol and water mix I use doesn't interact with the coating at all. In fact, it keeps it very clean.