Princess Hotel is a property owned by Kong Rong. There is absolutely illegal activity going on inside, but if Hua Anni were to investigate on her own initiative, it would be equivalent to telling everyone in no uncertain terms that she is acting out on behalf of her younger brother.
However, if she receives a report and acts under the orders of the director of the Supervision Department, then it is purely a matter of official business, and no one would draw the wrong conclusions.
She truly is his elder sister; how clever!
Chapter 39