Dozy,
I think you have to accept the fact "Droit positif" or Substantive law is the major legal method used throughout the world, the exception being, former English colonies where Common Law (Procedural law) is used. Even in the United States, it is a mixed bag in some States (Louisiana and other Southwestern States) that were not so influenced by the English colonization, some Common Law and some Substantive law are used to this day in those States. In either law, the objective is the same, only the methodology to reach the objective differs, the objective being justice. If you look at Continental Europe, Substantive law rules, although regulations vary from one country to the next.
I believe in France, Substantive law is used to determine whether a crime or tort (negligence for example) has been committed and to define what charges may apply and decide whether the evidence supports the charges. In other words, specific facts need to be proven true in order to convict someone or an organization of a crime or a tort. In some ways, it is like what a grand jury is charged to determine in the United States, except in France a judge is selected to make the determination.
So it would seem reasonable that all evidence gathered either by the French Court or by independent sources (BEA and the BEA report) would be examined and those persons or organizations connected to the evidence interviewed to clarify the written word.
At this point in time, I am not sure it has been decided what charges apply in the AF447 legal proceedings. I do know that a United States Court determined that the families of two US citizens who perished in the accident could not sue in the US Court system for damages, instead the Court decided the French legal system was perfectly adequate to make this determination on their behalf.