Sorry but this is anything but a non-issue, looking at the information in the publice domain, this is a systematic design failure.
1. The GCU control system fails after ~7000 hours.
2. It is a common mode failure so no credit can be given to multiple systems.
3. The failure leads to loss of all AC.
4. Loss of all AC is at least HAZARDOUS.
Therefore a target of 1x10-7 is fulfilled by a design stuggling to meet 1x10-4
Firstly the overflow error should be trapped at source. It adds complexity to design, but it needs to be done in safety critical systems.
Secondly it appears the safety analysis has not fully analysed all the software failures ... if the software design process guidelines for safety critical systems had been followed then this should have stood out like a sore thumb. This is the kind of thing that happens when people use the analysis from old designs, without re-validating the original assumptions against the new design.
In mechanical terms, if a fastner repeatedly loosens in flight there is something wrong, it is not acceptable to say that it didn't come totally undone so as long as we tighten it up each time it is ok, the fastener should be redesigned.
I have not seen a statement from Boeing that denies any of the 4 assumptions i have made, but I emphasise that I have no detailed knowledge so this is based only on the public domain information ... but based on that it really worries me, because it isn't a "bug" it is a systematic failure.