All this correlation with the event recorder, video, radio, surveillance, etc., is only relevant if his readily available text records show use very close to the time of the crash—and such use of course would be completely against protocol.
In my little world of Point Of Sale software, our system warns a user if their local device is more than 5 minutes out of sync with their primay server, because errors under 5 minutes on hamburger receipts are not a deal breaker...
Also, as noted by Paladin2, input and reaction times on a train are quite different than small vehicles we would be used to in daily life...
But, if you are in charge of an investigation that could result in criminal charges, you are going to be as methodical and careful as you can, so that when you release your findings, there will be little to no doubt as to the events in the timeline. (at least you should be, you could be a prosecutor from Baltimore...)