So hidden so deep, how did Miss Tang and that mysterious Non-human Team know the core was in the city center just by wandering around the outskirts of the city?
Could it be that there was indeed insider information? The Ancient City has been around for a year, and only a small number of people in Kangaroo Country know about its existence. They aren't even aware of the Cosmic Core, so there's no information to leak.
Thinking further inside... it could only be Miss Tang's father or someone working with him.
They have firsthand information. At that time, perhaps the 'pollutants' hadn't spread, and nothing in the desert was affected, so when Miss Tang's father was conducting research, it was safer than now.
Later... it's hard to say, so if we suppose Miss Tang knows about the existence of the Cosmic Core and intends to obtain it, she probably knows more or less about its use.
