I’ve encountered system errors on my stack of Pylontech batteries in the past, sometimes strange combinations like low temperature and cell imbalance errors at the same time. The errors went away when I reseated the communications cables between the batteries and also the CAN cable to the inverter. Those network plugs don’t fit very snugly in the sockets and it seems to me that if the connection is not great that strange things tend to happen.
Perhaps worthwhile swapping the network cables around to see if it has anything to do with cabling, just to exclude it as a possibility if nothing else.