No, don’t worry, Mara – with a 6 CHA, people who are on your side will be overwhelmingly likely to do what you say. (And people who aren’t on your side will probably hate and fear you with equal intensity – there’s nothing worse than a highly charismatic enemy. Just ask the political adversaries of Ronald Reagan or Bill Clinton, both of whom were probably about CHA 4).
But 6 INT and 6 COM characters will also be leaders and have people following their orders. At a certain point, genius almost always becomes charisma; whether or not someone has a conventionally magnetic personality, if they’re one of the greatest thinkers or generals of their time, they’ll be likely to attract intense loyalty.
My point above was that even uncharismatic non-geniuses can be successful leaders. Look at Angela Merkel – whatever you think of her policies, she’s the most powerful person in Europe. And little personal charisma to speak of.
I’d hold her up as an example of the difference in English usage between charisma and leadership. She gets people following her – or at any rate moving in the direction she wants them – but it isn’t because she’s got a natural skill at inspiring people or getting them to share a vision.