"Wait a second…" Re'Kha muttered, extending her Wind Qi perception through the other building. It was a regular restaurant frequented by the masses. There were no Harmonisers within to resist the effects of the Sha's hallucination.
In her case, Re'Kha had been monitoring the inn. So, the moment she noticed the people she was keeping watch over disappear, she knew something was amiss. Adding onto the fact that she heard the guards mention the Sha, she realised the danger immediately and used a palm projection to shatter the hallucination wrapped around her.
As for the Harmonisers from the Royal Clan, even if she hadn't saved them, they would have broken out the moment they noticed something amiss too. But, it would have taken some time, considering they were relaxed and in an unguarded state. That was why she rushed to their rescue in a hurry.