if redundancy systems fail, or their information is not transferred correctly, means being not received at the receiving end, it seems minor mistakes can end up with what happened. As the AAIB report has been very carefully worded, they may have already more information which is not appropriate to broadcast now in public. So if there was an issue with transferring information, caution warnings, alerts at some stage..at what stage have the pump switches been put into the incorrect position?
There are (at least 2) different sorts of Swiss cheese: one with few big bubbles, they are obvious, but then there is an other one too.