Even assuming there were FISAs (not likely), under your rationale of no one knowing about them then no convictions would be overturned because they weren’t part of the criminal case.
Your rationale for not releasing the info because it will affect so many cases does not hold up and is incorrect.
No, you aren’t properly understanding them. These weren’t criminal cases, they were anti-terror cases with evidence presented in secret to grand juries. The grand juries are special, all members being read into the FISA program, and they ALL would have known about them.
Every detainee at Gitmo who has a lawyer (i.e., every detainee) would have a motion in front of a judge immediately demanding a mistrial. These would have to be granted if the FISA was used for any part of the arrest or conviction, and all subsequent evidence would be “fruit of the poison tree.”
BTW, Gitmo just expanded-—NOT as “Q” says to accommodate more detainees, but to (as per a court order) allow more secure space for detainees to meet with their . . . lawyers.