You're mixing up two different evacuations. The whistleblower complaint about HHS employees with inadequate training processing evacuees was about the Wuhan evacuation, not the Diamond Princess one. Only about three of the Wuhan evacuees ever ended up testing positive for the virus, there's no reason to believe they were even infectious when flown back and none of the staff involved have shown signs of COVID-19. It's certainly possible that one of the people involved in the quarantine didn't follow precautions and was infected, even with full training, but I don't think there's any evidence tying the California case to it.