Wow...
I'll admit that I wasn't expecting the UI to be modifying active runtime data structures immediately for a rule as it is entered, piece by piece. Not on my Bingo card for the HE.
In thinking about doing that in other systems from my past, it would not go well unless there was excellent coding and synchronizing in the core program to deal with data structures that may provide conflicting states or data structures that would be incomplete.
If the UI is making immediate changes to the operational data structures I think it is a testament to the design and implementation of the HE Core code to handle all the unexpected issues that could arise and still maintain a solid operational state.
I have been involved with other programs that were problematic under similar conditions.
If the UI is not making immediate changes to the active rule data structures, I think the HE is still pretty cool and surprisingly flexible. I messed up a lot of rules dealing with lighting and it did not crash or flinch. Looking through the list of devices the HE can work with I found a number of use cases for around the house.
The UI question remains. 
Can the UI make immediate data/configuration changes to active automation sequences even if it is a multi-step process in order to have the full sequence completely configured?
I ask the question that way to flush out if the basic underlying HE rule capability is there for the company and community to use in their automation applications that can be loaded into the HE. Because, if it is there, we must assume that any of the automation integrations will be coded to use it. Which means that us, as end users, might as well assume that all apps are coded to use it. The final implication being that I, for one, need to be very careful when I call up any page for an automation within the UI! I need to NOT fat finger a data field or click on a field selection dropdown such that is it doesn't select something different than what I had working, unless I want to actually try something different.
In other words, I need to seriously pay attention and be very careful of my actions in the UI.
It also highlights, to me, the need to have backups exported out of the HE from known points in time that have all the active automations working as needed. This way, if I am doing trial and error work to modify an existing automation or create a new one and there are problems, I can roll the HE back to a known working point!
I am currently four days into being a HE owner, so deleting everything using the UI and starting over is not a big deal. A year down the road and it could be a nightmare to recreate from scratch, even with documentation containing screenshots of all the rule pages placed into OneNote.
To that end, I have read about the Hubitat subscriptions to backup configurations into their cloud.
After reading more documentation and poking around some, I came to find out that the HE makes a backup of the active configuration as part of system reboots and once nightly to local HE storage. I found some significant differences between downloading a local backup to my NAS and the Hub Protect/Cloud Backup subscriptions.
https://docs2.hubitat.com/en/user-interface/settings/backup-and-restore
At the moment, I plan to export/download a HE local backup image to my NAS with a filename that has the date and some verbiage about what it contains. More info about the backup I'll put into OneNote, which also lives on the NAS. The NAS is replicated off-site in case the house disappears. We did have an EF2 tornado go directly over the house several years ago. The house stayed on the foundation, fortunately, and none of us were injured. There was a lot of damage and some injuries spread over the 5+ miles along the track of the tornado.
If I end up with dozens of device pairings, it might be easier to use the subscriptions since it sounds like they keep the device pairings. I will need to re-read their subscription documents when the time comes. And likely ask more questions in the forum. 
The learning curve is steep, I have not found any magic decoder ring to help get to Nirvana faster, banged my head against a virtual wall a bunch, and waded through documentation that had some issues. I consider this the equivalent of the jigsaw puzzle that enthralls family members here.
As was said on Hill Street Blues:
Let's be careful out there!
Paul