Getting Automate to launch another launcher (other than Fire's launcher) is a 2 part process. The first part is to replace the Home button with one of our making that isn't locked into Fire Launcher. The second part is setting up Automate to read that button press and direct it towards our preferred launcher. If you don't have both parts, it will fail.
The script in Custom Navbar Key does the first part. That's why if it fails to work as expected you have to run an ADB command to get your home key back. The second part is an interactive portion that must be followed exactly to give all required permissions to Automate.
For me, it worked the first time, but then I had been playing around with those aspects already when Datastream33 added that method. I assure you it can work, and work well enough that it doesn't detract from the user experience. You just have to start fresh and follow ALL the on-screen instructions.