I agree with what you say, if it were an isolated event. Just one person killed by Balefire is no big deal. It won't unravel the Pattern. Every single place where it's been used can be rationalised. Kill a few Forsaken. Kill Darkhounds to save people from dying. Undo deaths caused by people. And...
When he channeled the full power of the CK in Winter's Heart, he and everyone else were pretty sure that with such an amount of saidin, he could've literally cracked the entire world. We're talking thousands of times the amount of power he could channel unaided. We've seen him use lots of...
But Rand didn't use the full force of the CK, did he? IIRC. If he had, he really would've broken the world, since that's how powerful that sa'angreal is.
That sounds horribly stupid. Launch such a terrifying strike of balefire at someone, and you really have no idea what's going to happen. When Rand Balefired Graendal's hideout, the weave was seriously damaged and nearly came apart. A full circle of Aes Sedai wielding powerful sa'angreals could...
I think she's dead, for all intents and purposes. A vegetable. Her mind is dead, broken. Remember that Healing the mind isn't the same as Healing the body. Semirhage was one of the foremost Restorers during the AoL. Graendal was the best at Healing the mind, and there were some thing that were...