If this case is closed (via Death Certificates and CoD indicating a non-criminal CoD), then the private records of the victims are not going to become public.
If the case becomes a criminal case, then the investigation will be tight-lipped, because otherwise LE and the State will be accused in Court of manipulating the public narrative.
The determination of CoD is not easy in a case like this. Toxicology will be done, at least on JFR as driver and owner of the vehicle, but I'm not optimistic that the bones will yield up much information. Still, the attempt has to be made and given the state of the remains, it will have to go to a special, likely university-based laboratory for analysis. San Diego County has some of the best kit and best experts in the nation, I'm sure they'd like to at least try and see what they can find in those remains.
We are not entitled to phone records of other people in California (or, I believe, in any US State). LE has a special duty to maintain privacy of innocent citizens. Their lives are not an open book for the public to review. LE has an obligation NOT to share people's private information. Just because someone dies in a mysterious way does not mean that LE can just break the rules, policies and laws regarding the dispensation of information to the public. Next of kin IS being told what's going on, per our VI. Our VI doesn't have to share it, either.
If this is determined NOT to be a criminal matter, then the autopsy reports can be requested to be sealed by the next of kin. If for some reason, the family finds a reason for a civil suit, then they can allow their lawyer to order the autopsy reports, but they must be made public at some point (so that the defendants can defend themselves). IME, this availability of the autopsy report to the plaintiffs happens early in the case, but not before the nearly obligatory Motion for Dismissal/Summary Judgment. My assumption would be that in such a civil case, we'd be able to surmise quite a bit from the Plaintiff's complaint and choices about whom to sue.
We the public are not entitled to telematics from people's cars, when there is no criminal case and then only after a Court decides the public gets to see such things. I"m not sure how the idea that LE "should" release private information about deceased people is getting traction. That's an extraordinary ask. I do understand that people want to know, but we are not entitled to know at this point in time. We may never know - the families will, though.
At any rate, the process of determining WHETHER this is a criminal matter appears to be still underway. When Cause of Death is entered, we'll move to the next phase (either a criminal case and its rules of procedure; a civil case; or no case at all - if the CoD indicates wilderness misadventure and the families decide not to sue).
Most of us have seen cases stay in this limbo for six months. Or a year. Or more. No one here is next of kin, IMO. Only next of kin has standing to get information which, as we know through our VI, has been happening for Fang's family in Belgium. Other people, like ourselves, are NOT entitled to what the family is entitled to. I think this is both legal precedent and common courtesy.
How long does it take to get all the autopsy results and truck results? I can only guess - but six months is not an unusual period of time; with the truck's situation, could be even longer. Things are going slowly right now in the forensic world, post-COVID. How long to really scour the land for more clues, once the telematics and the phone data are completely analyzed? Anyone's guess. I'm sure the area around the truck and the projected walk from the truck to Harper Canyon have been closely looked at, but new facts from the truck (about time of day when it crashed in particular) could lead to more searches in Anza Borrego, down flood channels, etc. Just because the bodies are found in/near Harper Canyon does't mean that some evidence wasn't moved elsewhere by the floods.
What kind of civil action could be brought?
It could be, say, against Anza-Borrego SP/the State of California. My own work as a consultant in missing person's cases on public land has been in the context of National Parks being sued or notified of a pending lawsuit in civil cases. None of them resulted in the NP's having to pay out anything - just change some ways they did things. If a civil case is looming, that too will proceed slowly and information will NOT be public but some public allegations would have to be made
Then, LE and Anza-Borrego will be even LESS forthcoming, all around. Since there seems to be a group of people posting on SM and highly critical of LE, it's even possible that LE could be sued.
I think all of us know that this is not going to result in more public information coming from LE, but will result in less information while the case drags on. OTOH, the litigants might be able to share what they learn in civil discovery with the press, if that's what they want to do. That would be a year or so down the road, IME. It would be normal for a Plaintiff's civil attorney to do exactly that, even perhaps hiring a consultant to figure out the best way to prime a local jury for a big judgment. Personally, I don't see a case against either SBC or SDC going very far.
But...California may well be the most litigious state in the world - we surely do have that reputation in many people's minds.
My heart goes out to the families, particularly the daughters, in their quest to understand what really happened. This slowly moving process is a feature of nearly every case in California, not just on WS or Reddit.
Enough is known, though, that at least the families aren't completely in the dark - the way, say, the family of Kristin Smart were, for decades.
So we wait. For the autopsies to be completed and CoD entered. And IME, even if a civil case is filed by someone with standing (it will be thrown out if the Plaintiffs don't have legal standing), once the autopsies are obtained, the law firm will hire forensic consultants to explain those harrowing results to the lawyers, so they can proceed. That takes time too.
IME as a forensic consultant and professor of forensic and legal anthropology. Also, IMO, since like everyone else, I don't have all the facts of this case.