That part I am not sure of. I installed 2024.1 on my local computer and ran into the same issue with not being able to change the target. I have %ALL access so I wouldn't think it would be a permissions problem. I briefly demoed it to our developers. Everyone liked the old version better. I turned it off and haven't looked back.
We recently upgraded our environment to 2023.1 which included the new rule editor ui. We immediately disabled the new ui to revert to the version that our team was comfortable with.
https://docs.intersystems.com/healthconnectlatest/csp/docbook/DocBook.UI...




For the hurdles section:
For the outstanding questions:
5. In order to run the complete test again where messages are completely reprocessed, you would need to delete the TESTING_NAMESPACE (whatever you called it in the ConfigureNamespace method), copy the original IRIS.DAT from your source to your folder, then start the process again. That clean up could probably be added to the documentation.