What seems odd to me is that this "investigation" takes more than a few minutes. How is a system that allows easy auditing and checks and balances also the same system that takes weeks or months to determine who accessed specific records.
I think it's unlikely we'll see any raw data. Chances are that if there was any investigation going on into anyone on Trump's team (which we know there was), then those individuals showing up at Trump Tower for a meeting creates a metadata correlation to Trump Tower. Hence Trump's claim of "wiretapping Trump Tower" would seemingly be trivially true if even the simplest metadata link between, say, Flynn and Trump Tower were followed or considered potentially relevant by any analyst.
I agree with regards to viewing the data. But that would imply it was a matter of asking NSA to check the audit trail. With a topic so politically charged, I would hope that they would instead get an independent committee with proper security clearances to get access to the data in their SCIF and be able to ask questions to fully understand each action taken and assure it is all above board. I do not have direct knowledge of how such an investigation would work, but my point is that retrieving the audit trail is probably an easy aspect of a longer process.
But this is precisely what's problematic about the metadata program, it casts a very wide net which deprives many innocent bystanders of their rights.
However, there is an audit trail in the system. As an investigation will occur on this matter, I am sure that cleared representatives will have access to this for review.