An hypothesis - spoiler potential.
It is Lion’s Arch. They wouldn't have created plot loophole where Scarlet tries to weaken the Lion's Arch defenses, long before she builds a probe to find out she needs to attack Lion's Arch, unless she is actually going to attack Lion's Arch.
Maybe it’s to throw off the players. She might actually be preparing to slay a dragon. But I wonder, if this is the case, did she already knew the dragon’s location in the first place? She needs a puppet in the LA council because she deemed the current ones as incompetent or would not cooperate with her or would not believe her? Why would she put probes all over the world if she already knew the location? Making sure she hit the right spot? What about the thaumanova reactor, the new instance says the cooling rods were “steeped in dragon energy” and the reactor taps into the leylines. So does that mean a sleeping dragon is connected to those leylines? What about the asuran gates and waypoints? Do they tap into these leylines? And if the dragon is connected to the leylines, how could it have a far reaching influence all over Tyria and even in the Mists, considering the other dragons have limited influence? Could it be that the dragon Ceara/Scarlet is afraid of is the monstrous mother of all dragons? Could it be that there is a seventh dragon, far more powerful than the rest?
I just think Lion’s Arch is simply in her way. She’s psychotic enough to completely disregard the people living there in order to achieve her goal, which ultimately is the goal of the dragon she thinks she’s going to kill by ultimately feeding it the magic it needs to fully awaken.