> When the Iryo reported to be stuck, all the trains in the line should have been notified to stop once more
That would have meant that the dispatcher would have been aware that they already ordered a collision before. If a train stops no accident will happen, unless it could have happened regardless. Yes, such a decision would have prevented the accident or lessened it's impact, but the absence of it has not caused it. The error was already done before.
> they already ordered a collision before
What do you mean? "Everyone crash now"? Makes no sense. "Tried to solve"? There was no collision before.
The situation seems to be that they stopped the trains due to a problem somewhere. When they thought it was solved, they commanded all of them to move again. And when one reported to be unable to do so, they failed to stop those that were around it. Or that is what the leaked conversations suggest. Do not discard this was tactical leaks to blame a scapegoat. The newer system should be running.
I say around, because news mention that a third train could have crashed into the wreckage of the other two. It was moving in the other direction, towards Madrid. Luckly it stopped when the electricity failed. It would have been like the accident early this year, when a train hit other that just had a derailment.