> And what are the systemic practices in place that led to people not following the official protocol?

I guess we'll find out. Apparently one of two drivers who were given the go ahead for normal operations requested additional confirmation because he or she (rightly) thought go-slow was the expected response for transit resumption under the fallback protocol. Some incompetence in the control authority Adif, then, but I'm sure that'll be the focus of the inquiry they will no doubt have.