I haven't caught up yet, and I'm sure someone has already answered you. However, I've been vocal about being sympathetic towards HH, so I'll give you my 2¢.
Personally I think when we are discussing a crime committed by any person of their own volition, we have to first think of justice for the victim and any other people affected by the crime. Thankfully we have laws that tell us which crimes we can objectively call worse than other crimes and we have a system that is set up to (theoretically) punish worse crimes with worse punishments. I'd go so far as to say *most* of us have an inborn moral code and there's a line we draw between what we can and can't do in good conscience.
So, for example, if I had murdered someone when I was a teenager, I would expect to face some serious consequences, regardless of my dysfunctional childhood.
But it's noteworthy that minors are, by law, usually treated differently - less harshly - than an adult guilty of the same sort of crime. Society knows and accepts, in general, that minors are not fully grown and don't have fully formed areas of the brain that control executive function.
(I'm pretty sure that last sentence is grammatically incorrect, but hopefully you get my gist.)
So, subjectively I can feel sympathy for someone and still objectively say they were wrong and should be held accountable. Sympathy can lead to compassion, in how a criminal is treated and/or perceived, while still saying the criminal is guilty.
So, this is getting long. In this particular case, I do not think HH participated in the murder of Gannon. If she struck him, cut him, shot him, then she should be held accountable for that. If, however, she knew some things that might have been incriminating for her mother, and could not bring herself to share info with LE, it is directly related to her mindset... namely a mindset that has been forged into her very being since before birth, by an evil person. And I'm positive that, in that position, I, having had a similar mother, would have believed her (incredible, fantastical, absolutely illogical) excuses 100% over my own understanding.
Storytime. Listen, at 26 I didn't invite certain relatives to my wedding because my mother was feuding with them. These are some of the nicest people! But showing her my loyalty, even without any idea of what wrongs they had done her, was of utmost importance. I didn't need to know the details; my heart simply broke for the pain they caused my poor victimized mother. And.... I felt loved when I told her they wouldn't be getting invitations. I was so trained - like a dog - to be unquestioningly loyal and obedient and blind - and all for a bit of affection - that I behaved like a b**** to these people who had done me no wrong.
Was I responsible for treating them badly? Hell, yes. I should have grown up a lot sooner and gotten my head out of my a$$. Can I still have sympathy for the poor girl who grew up with that sort of training? Sure. It helps me explain and understand... It helps me grow into a better person.
If HH's only crime is not cooperating fully with LE at first, I believe it's because she could not bring herself to disbelieve her mother. Where would she get the capability of making that stand? It would be like a stranger asking a loyal dog to attack his master while his master is feeding him a steak and rubbing his belly.
There's a difference between committing a crime oneself vs. believing a crime was committed by another and promptly taking that to authorities if you've never betrayed that person before. It's a gradual and slow process of realizing, and denying, and hoping and finally accepting. If LE handled it right, HH is now fully cooperating. But how they handled her is entirely dependent on understanding where she's coming from.