So I hadn't realized that Canola2 had its own "Remain Lit While Charging" setting. I've now turned that off, but have the system "remains-lit" still set to "while charging." Things seem to be behaving as expected now.

With Canola's setting turned on, I was frequently seeing that the Lock&Blank and Blank would not blank, and also that Lock&Blank would not consistently lock. It seemed that, for instance, after seeing the "an app may have paused blanking" notification and then "screen is locked, will blank in 60 seconds" notification, that screen taps would be recognized. Then, on pressing the power button, a notification "screen and keys active."