Thanks for the assurance and the pointers, Green and Spockster. It does appear that serious harm was done.
I went out this morning and first played with the old ACCTs. They work as expected and did in fact help me better understand how they work. Which is to say that I now better understand the wording of the CAUTION note in the manual - particularly the "non-return" part. So the spring applies outward pressure to the chain guides and stays at that pressure. It doesn't spring back or "bounce" with the fluctuations in the chain. In that respect, they hold firmly just like an MCCT; the only difference being that they extend over time to compensate for chain stretch/wear. (Feel free to correct me if I'm wrong about this.)
Incidental side note: The Clymer manual differs from the factory (pdf) manual when it comes to reinstalling the ACCT. Instead of the simple method of holding the screw with the small screwdriver, Clymer, for some inexplicable reason, suggests buying or making a "special tool" for that purpose. One would think that if Kawasaki sells a "special tool" for that purpose, its manual would suggest it - not Clymer's.
Moving on, I then had a fresh look at my front cyl. MCCT - the cylinder I feared that I'd damaged. To my great relief, the "tension" screw did meet with resistance against the chain guide, and without even a full turn beyond what I adjusted it to the other night. What's more, I backed it out while running and heard the chain rattle as expected so was able to adjust it confidently from there.
Oh yes, and, not sure if this matters or not, but I saw nothing unusual in the course of changing my oil recently; no evidence of aluminum or rubber in the oil from any possible guide damage.
I'm looking forward to better night's sleep this evening! And tomorrow I'm planning to go for a nice ride along the coast.