I am interested in understanding whether the C of A was valid, given the discrepencies noted by the AAIB report. If the C of A is not valid then I doubt that you have insurance for the flight.
In any case the lack of a night rating might be enough for the insurer to say that there was no qualified pilot for this flight and hence that the insurance is not valid.
Another good reason to keep the paperwork up to date and only operate within the rules: you bend it and the financial cost, including collateral damage, falls on you.