I don't think Kagha needs to be changed. In D&D terms she's someone who's on the brink of a shift of allignment but she's not completely evil yet. You can convince her not to murder the child and later on you can also redeem her if you do things right. In fact I did so twice in the course of 2 different playthroughs.
While that hardly makes her less unlikable, I think people need to come to terms with the fact that she doesn't intentionally "murder the child" as many keep claiming.
The scene is intended as her threatening the girl with a punishment, with the snake being there just as a tool of intimidation... Except things go out of control.