Without knowing all the details, Baldwin's culpability (ethically and legally) is the most up in the air.
The director supposedly told him it was a cold gun as he handed it to Baldwin, and industry standards don't expect actors to practice gun safety when handling "cold guns". So you have Baldwin going "And I'll draw like this and pull the trigger." as they work to properly stage the scene, only for a live round to be fired at the camera.
Absent some extenuating circumstances, it gets really hard to say that Baldwin is liable for the shooting.
Honestly, the Director is the one most at fault. He picked up a gun off the armorers bench/cart/area without the armorers express permission, failed to check that it was actually a cold gun, and handed it to the actor telling him it was a cold gun for a scene where it was intended that the actor would pull the trigger.
Why the armorer left a live gun where someone could grab it is another question. As is how a live gun ended up on set in the first place.
But absent the armorer saying to the director "yeah, grab that one. It's cold." or words to that effect, it's hard to say that the armorer is liable. I mean the director took the gun from her area without permission.
Honestly? If I was on all three juries. Baldwin gets found innocent of anything (absent any liability related to his role as producer). The Director is guilty of manslaughter as his negligent actions directly and foreseeably resulted in a death (especially given the previous issues with gun safety on the set). The Armorer might or might not be guilty of something depending on the specifics, but short of her expressly telling the director it was a cold gun she isn't liable for murder or manslaughter.