Hi, Angela -
I am not exactly an expert on troubleshooting such matters, but I can give you some thoughts based on our own experiences with the Clarity PHEV gained in 6 months of ownership.
First, it isn't clear to me what the charge state of your main (big, traction) battery was when you parked the vehicle.
We recently (last month) went on a 3-week trip to Europe and left our car in regular airport parking for that time. Following recommendations from others on this forum, I made sure that the main (traction) battery had a charge level of about 50% or higher before I parked for a long interval, but then parked normally with no chargers in sight. Three weeks later, we arrived back at the departure airport -- no problems. In fact, we were even able to monitor the car and its battery charge state on the HondaLink app on our smartphone remotely from Europe, giving us some further assurance that all was well with the car.
Second, we did experience the multiple fault issue early in our ownership, but the s/w updates applied then by a dealer seems to have solved all of that. We haven't had a recurrence of that issue at all. But, frankly, given that your car's 12V battery had somehow been depleted, it is not much of a surprise that you got multiple error messages anyway. I would have been more alarmed to get no messages at all under those circumstances.
Finally, it might be worth checking to see whether the 110V charger was plugged into a live outlet during the whole time of your absence. I am not sure, but if you had some localized power outage or maybe a GFCI circuit breaker trip for some reason, the power to the car could have been interrupted and thus the charge. In that case, monitoring the charging state via the HondaLink app might have remote alerted you to that issue. That said, the car's manual (p 458) says that after a power interruption "...the vehicle will resume charging once power is restored" unless the traction battery has fallen to -22F or below -- not likely in Scottsdale, even in a big cold snap. Still, if a GFCI or other breaker had somehow tripped, the power to the charger would not have been restored until someone manually reset it.
Or, something else weird happened that a dealer may be able to figure out for you and solve. An update on this forum from you after you have figured it all out would be welcome information for many of the rest of us.