Yes, they might define these differently in the Star Wars universe, but we never see Ciena participate in attacks on civilians, abusing or killing POWs etc. Does the New Republic feel just being in the Imperial Navy makes you a war criminal? If so, that would make Thane also a war criminal for having been part of them before he defected, plus any other defectors. All we read they listed was that she served in various battles. None featured her doing the above. Ciena herself thinks she is a war criminal. Why? Is it like the SS after World War 2, with the entire group declared a criminal organization? Well, just like Thane says, they can't prosecute them all (plus the same point about that would mean he's also a former war criminal). I just don't get what the author apparently thinks is obvious. This isn't clear at all. Even if the above (entire group declared criminal) was true, you'd think they would only prosecute people who had actually participated in atrocities, not just were a part of the organization which did them.
It's very likely that Ciena is being charged as fighting on for the Empire after Operation: Cinder and for Gallius Rax's illegal government. The Republic doesn't necessarily recognize the Empire under Rax as the actual Empire. It could be hyperbole, though. The assumption being anyone of that high rank who was endorsed by Grand Moff Tarkin himself has to be a psychopath. It wouldn't help that Ciena will also not cooperate in the slightest with the Republic whereas even hardcore Imperials would due to her Blue-and-Orange Morality.
I don't think so, it said she's charged with past war crimes in the book. From what I recall anyway.
Since Ciena was part of the command staff on Vader's flagships, it's possible she is being charged as an accessory to the actions committed while she was onboard. Seeing as the Executor was completely destroyed at Endor, she may be one of the highest ranking officers from that ship still alive at this point.
That could be, I just wish they'd been more clear and gave specifics of what the charges were.
