Without understanding the (technical) reasons why it is not possible to store zone ordering mapping in the controller itself, it would not be my personal preference to pursue the proposed path of storing such critical information in the cloud. I suspect that without a functioning internet connection the mapping could not be retrieved at the time of irrigation, messing up important dependencies that could even result in damaging a well pump in my case. Very undesirable situation.
My observation: zone reordering/mapping seems to be an advanced feature that may not be relevant to the majority of users. Though nice to have, from a developer viewpoint it does not seem to be need to have and should therefor only be implemented if reasonably easy to realize.
Perhaps something to keep in the back of the head for when a complete re-write of controller software is necessary (at some point in the -distant- future?) and implementation becomes feasible with storage in the device itself