My guess is that someone changed the indicated airspeed (IAS) instead of the heading (HDG) or altitude (ALT). That explains why nothing was recorded, no one wanted to confess.
but they flew on from Maui instead of turning around. if they’d turned around then the cockpit voice recorders would capture the incident. instead they had 5 hours to get their story straight and no actual recording of the incident.
The autopilot parameters and control inputs would still be captured by the flight data recorder.
Aviation as an industry is built on blameless, honest post-mortems. There's a strong safety culture, and pilots are encouraged to share their mistakes so that other pilots can learn from them.
In most cases, filing a safety report will protect the pilot against any retribution from either the airline or the federal government. At worst, they'd be asked to undergo additional training. There's no reason for the pilots to engage in deception here.
Which does draw attention to the still anemic CVR storage size. I recall incidents where the length of the flight was longer than the CVR storage, or the pilots forgetting/failing to pop the CVR breaker, leading to events being overwritten.
In this day and age it does not seem reasonable to have less than 24 hours of CVR storage - it gives time for any flight, and also space for people forgetting to pop breakers.
