At least in my jurisdiction (CA) attempt and manslaughter don't fit well together. Voluntary manslaughter means that you killed someone in a sudden quarrel or heat of passion. It's hard to imagine how one can attempt to have a sudden quarrel. It can also arise out of an attempt at self-defense that is excessive. Again it is hard to see how one could attempt to be excessive. Involuntary manslaughter doesn't work at all. How can you attempt to do something involuntary? I suspect the charges are something different.
The family of the victim are trying to do what they can, but it is the lawyers at the State Attorney's office who will decide what charges fits and what charge they can prove.
Most likely, if the victim is in the hospital, the charge will be a form of battery. Simple Battery is a misdemeanor but there are forms of battery, when done with a weapon or if injury results, that are felony class crimes.
Of course, battery charges of all types have defenses, such as self defense.
I would say that the someone you know should not discuss this incident with anyone besides a lawyer and certainly not with authorities.