the start of the "centre track" seems to show substantial burning (blacker than later) perhaps the right engine detached from the plane there and there was a fuel spill causing the scorching?
I believe running engines when detaching tend to continue having a forward motion (El Al Amsterdam) for a short while
The tracks start some way off the runway, suggesting that the touchdown was on the grass, not the runway. No visible loose parts on the runway.
So uncommanded trust reverse on the right engine with a hard landing on the grass, could this lead to the engine detaching?