Ok, thanks for the tip on N.B. I learned something new today!
Please note that my original post included my solution as well. I am/will be posting tidbits (problems I encountered, and how I solved them) in this forum for the sole purpose of building up the searchable archives/information in our new Power Apps forum. If at any point Jon would rather I don't do this (following instead the tradition of only posting if you have an actual unsolved question), I'll be agreeable to the change, but for now I am trying to help get the content started. Hopefully this will drive traffic for people who have similar problems with Flows and come to AWF for solutions.
As for their usefulness, I was skeptical at first, too. Access macros are built into the front end application, and are limited by the typical constraints of user-driven interface events. Flows are really nothing like that: Flow operates at a much higher level - running on the server, with no user interaction needed, and perpetuating the permissions of the individual who set up the Flow. I would compare its usefulness to be more along the lines of SSIS, and in fact, it draws many parallels to SSIS, since you can essentially create packages that do many things, and can even hook into API's, .Net plugins, Web services, as well as all the standard things (update database records, administer permissions, maintenance, send notifications, etc).
Alternately, you can trigger a Flow from within a Power App, but so far my flows have been of type=Automated (based on a Trigger, of which there are 100's to choose from), or Scheduled (runs on a set schedule - every minute, hour, etc).
Currently I seem to be doing a lot more in Power Automate/Flow than I do in Power Apps. I haven't had a good case yet to use Power Apps, so have only so far created trivial test apps and taken all the tutorials as well as keeping up with content in the Microsoft forum.
Flows, on the other hand, is something I'm finding already quite useful in order to create server-hosted batch jobs, record updates, workflow triggering, notifications, etc.
My excitement is more along the lines of acceptance. My company has opened up the usage of Power Apps and Power Automate, so because of that, and believing that their use will drastically increase with time, I've decided to get involved earlier rather than later.