In your opinion, which hero has the most charisma in the campaign?

Instead of Isabel, he put Biara in her place. And in doing so, he struck at the enemy's weak spot.

Yes, but at the same time, Railag was calmly taking advantage of her, while Biara was causing trouble in the guise of Isabel.
In general, it's not very clear how the real Isabel was able to calmly leave with Railag, and how these slowpokes managed to take Biara with them. Unless, I have a version in which, while everyone was sleeping, Railag suggested that Isabel leave the group, and when they left, Biara took the opportunity and took the place of the real queen. But in that case, luck prevails, rather than the charisma and coolness of this very ruler.

And still, no matter how you look at it, the most awesome of all the characters is Markel. Yes, he was lucky in the sense that such a disaster happened in the kingdom, the king died, and a stupid necromancer took the throne, but the way he took advantage of all this is simply amazing. Although it's a pity for the old man, because in the end he was still defeated by the forces of the beaver. However, as I think, if such a situation were real, he wouldn't have given in so easily. So, no matter what anyone says, Railag and even this Kha-Belekh of yours are quietly taking a backseat to the cunning necromancer.

Added 1 minute ago
And yes, in my opinion, Kha-Belekh looks quite normal, but it's all a matter of taste. So I don't think it's worth continuing this discussion, because in the end everyone will be right for themselves.