"After not doing any dark side stuff the whole game, Cal SUDDENLY uses dark side out of nowhere." Yeah it's almost like Cal has been steadily whittled down the whole game, from finding out that his efforts against the Empire have amounted to fuck all, to the death of his team on Coruscant, to Bode's betrayal causing the death of not one but TWO mentor figures (one of which being the woman who pulled him out of the trash heap he was hiding in and gave him a purpose in life) and now the man who caused a lot of that is getting away?
NO SHIT he's gonna get angry, this isn't out of nowhere at all. It's the culmination of all the fucked up shit Cal has been through up to this point.
"After Merrin tells Cal not to go full Dark Side, he still uses it against Bode." It's one thing to calm yourself down when the source of your anger is not present, it's another thing entirely to do it when said source is beating you to death and will likely kill the woman you love if he does.
"Why is Bode's daughter just okay with Cal when he killed her father in front of her. Yeah it wasn't his fault 'cause Bode kept pushing, but she shouldn't understand that." Why shouldn't Kata understand that? She literally says, before she leads Cal and Merrin to Bode
"I'm sorry Papa hurt you" strongly indicating that she was fully aware of the kinds of fucked up shit her father did in her name, not least of which because she was there to hear the conversation. Never mind the fact she was present for his death and saw Cal TRY to spare him, even Kata herself was trying to plead sense into him and got Force Pushed for her efforts.
Or are you criticizing her not being more torn up about it? I mean she likely hasn't had time to really process it yet, the game ends right after he dies and given she's already lived through the death of one parent, she's likely just not trying to deal with it at the moment. It will probably be a big part of whatever arc she's given in the next game.
Of all things to criticize Jedi Survivor for, it definitely shouldn't be ending.

ha