Basically, every FISA application makes assertions of fact, which are presented to the FISA court, the FISC, in support of the application. Naturally, those assertions of fact are supposed to be supported by, well, evidence that can be confirmed. Horowitz says:
As a result of our audit work to date and as described below, we do not have confidence that the FBI has executed its Woods Procedures in compliance with FBI policy. Specifically, the Woods Procedures mandate compiling supporting documentation for each fact in the FISA application. Adherence to the Woods Procedures should result in such documentation as a means toward achievement of the FBI’s policy that FISA applications be “scrupulously accurate.”
OK, fair enough. The FBI hasn't been "scrupulously accurate." Mistakes were made. But that doesn't mean that jobs will be lost, or anything drastic like that. Scrupulosity is for small minded people, anyway. The FBI maintains that the mistakes weren't "material", and maybe that's the point. Under the FISA regime, mistakes are mostly administrative miscues. That's the beauty of FISA: no real accountability for the bureaucrats. Isn't that the ultimate bureaucratic dream?
However, in the bigger world of politics this interim OIG report comes at an awkward moment. The Deep State of the Intel Community failed to get the "clean renewal" of the Patriot Act expansions of FISA before Congress recessed. In the short term, that may not make too much difference--if a clean renewal happens when Congress returns.
Let's not quibble about the materiality of the mistakes--nobody knows at this point. What we do know is that material "mistakes" were made, deliberate misconduct was committed, in the attempted coup against Trump. Coming on top of that, this report gives an impression of the FBI as an organization that is either unable or unwilling to follow its own policies--much less the laws enacted by Congress.
That impression will not make renewal of the Patriot Act expansions easier. To the contrary, it will increase the pressure on AG Barr. Barr was a proponent of a "clean renewal," assuring legislators that he would institute new rules and regulations and guidelines to remedy the mistakes that were made--to make sure that in the future mistakes would not be made. The impression of the FBI that this report provides, of an organization that is either inept or devious, will increase the pressure on Barr to agree to hardwiring safeguards into actual legislation, rather than ... new rules and regulations and guidelines.
Where this rubber will meet the road will be "business records" provision of the Patriot Act. That provision allowed for NSA to collect, well, everything. The same coalition of liberals and conservatives that blocked a clean renewal will want, now, to do something about the FBI's previously almost unfettered access to that vast pool of data.
I suggest that, rather than worrying about the few details that have actually emerged from Horowitz's latest report, we should focus on the legislative process. While I have argued that FISA is, itself, unconstitutional, I have also argued that it's probably here to stay. I'm ambivalent about that prospect. On the one hand, I prefer that the Constitution be adhered to. On the other hand, I know that there's no way that the Framers could have envisioned the National Security Surveillance State that we now face. Legislative restrictions on that mostrosity--restrictions added to an unconstitutional law--may be all that we can hope for.