I just noticed that the Shortcuts app in iOS (possibly iPadOS, but not macOS) has a feature I've never noticed before (which could be because I've been running the newest iOS only for about a month now) that allows me to create an automation in Shortcuts that triggers upon receiving text messages or email messages from anyone or from specific people or when the subject contains specific text strings. If iOS can trigger on those things, then I'm hopeful that KM can also trigger on those things. There's probably an API that Shortcuts is using to trigger on such events. I would really like to see KM use that API to implement the same feature.
Worst case, you can always just have the text message trigger a Shortcut that runs a KBM macro (via URL or Applescript), right?
Yes, I did think of that when I wrote my original message above. I wasn't sure if it would work because I wasn't sure if I could get Shortcuts to pass all the data from the message/email or not. So being unsure, I didn't mention it. But you are right, and it's a very good point.