B) The FBI doesn't keep logs of who accessed what because a judge wants it. They keep logs on who accessed what because they want to know who leaked documents to reporters. Something like the Fincen Files leak: https://en.wikipedia.org/wiki/FinCEN_Files is investigated by figuring out everyone who opened the files in question.
The FBI has even more important information than this, in particular the identities of confidential informants and undercover agents. Those cases are actually more complex because they are highly protected- with good reason, if someone unauthorized accesses this data it can get people killed- but desperately need to deconflict: there have been cases where a FBI office in City A was using a undercover agent to try and trap drug smugglers in City B, while a confidential informant in City B was trying to trap gun runners in City A, and no actual criminals were involved.
Then nobody can prove who/what/why data was illegally accessed.
And if some judge forces you to turn over those 24 hours worth of logs, you fix the ACL's and respond to the judge tomorrow, when the logs show nothing unwanted.