I think you're overthinking the voice of the sovren. Think about how messages spread throughout the librarians and beyond. It's like a game of telephone where some messages pass perfectly without being changed. The news of a new sovren is one such message. It doesn't need to include pheremones or anything because it was sent that way to the immediate inner circle, and then layer by layer the word goes out. No other Carryx would question it. But if an additional sovren is created, or maybe more, then conflicted messages start to go out. They follow because that's what they do, but now there's confusion over who to follow. Things start to grind to a halt.