My version with a few differences.

The train hits the truck and trailer either just before or at the crossing. The trailer goes through the left island crossing signal and gate mech and ends up to the right on the far lane of the crossing somehow on fire. The truck is wedged under the front of the cab car and is sheared in half/spit out just over the crossing, also ending up to the right.

The cab car has derailed and the front of it is veering to the left. It goes through the fence which probably was inconsequential because I think there was a dirt bank beyond the fence that catches the front of the cab car. Presumably the rear of the cab car was still on the rail coupled to the Bombardier car. At this point I think I believe everything was still upright. The question is what happened to the rear end of the cab car?

I think after the cab car dug into the bank it snapped around disconnecting the Bombardier behind which threw it off the track probably spreading/turning the rail and causing the initial track damage. This means that the end of the Bombardier car furthest from the rail out in the road was actually the leading end coupled to the cab car. Can't really tell by the photos if it stayed upright until the last or was already on its side sliding through the dirt. When the cab car hit the bank either it then rolled and the rear of the car slid along the rail or possibly it went into the air. When the Bombardier car went over it pulled the car behind it over in part due to the angle. Fortunately the coupler/draft gear failed on the third/fourth car connection and the weight of the engine helped keep the fourth car upright.

The whole thing would have happened in seconds with unimaginable violence. It is quite the miracle that it was a survivable wreck. I'm not yet convinced how much of the credit goes to the Rotem CEM design though I imagine that the interior arrangement improvements learned from Chatsworth and other wrecks helped reduce the injuries. Now to wait for a year and a half to see what the NTSB says besides PTC, seat belts and rear facing seats would have prevented it.