#fafafa matches the background. Observe!
You say that, yet she routinely blocks those types of shots with her sword's wind barriers. She can detect the disturbances in the air directly. She did nothing to activate the barrier besides invoking it, but it hit the exact spot the crossbow bolt came it at. Without her moving at all.
Maybe the others are vulnerable to assassination, but we haven't seen any of them yet. I don't believe for a second that Eleonora shares that weak point.