> After your final fix, if I understood you correctly, we will no longer have to open Terminal?

That's correct. That's the way the Launcher works on previous version on macOS.

> will it ever be possible to not have the terminal run in the future?

That's the way the Launcher works. It's a very simple-minded application.  Essentially all it does for you is to provide an easy way from the Finder to run a Python script in a terminal window, i.e. by double-clicking or by drag-and-drop. Like on other Unix-based systems, Python on macOS is typically used as a command line program that runs under a Unix shell in a terminal window of some sort.  Python itself does not provide a macOS GUI application interface; that is something that IDLE does (and other third-party IDEs that support Python). The Launcher app dates back to the very earliest days of Mac OS X when Python for Classic MacOS (System 9) was ported over. The Launcher is not really used very much as far as I can tell and its age shows with some usability and even security concerns. If you are comfortable using a terminal window and a Unix shell, you may find it more convenient to just run scripts directly there rather than indirectly using the Launcher, e.g.

$ cd Documents  # or whatever Folder
$ python3.8 your_script.py

Or, to open Python in interactive mode, where you can enter statements and immediately see the results:

$ python3.8

If you prefer a full-featured dev environment, you can use IDLE.

> Is there no way to edit a previous comment?

On the current bugs.python.org, no, sorry!

> the Launcher Preferences window also opens when I run a script.  Did I miss a setting?

As far as I know, opening Preferences is a "feature" of the Launcher and can't be prevented.