1) All he said that was busted was that Graendal being balefired wouldn't undo Asmodean's death even if she were the killer. As those above have let you know, you misinterpreted.

2) Jordan has gone on record to say that one balefire cannot undo another balefire. It wouldn't matter if they were seconds apart. If Person A balefires Person B and then Person A is immediately balefired themself, the previously balefired Person B does not come back to life. He's been asked about this.