The 'Exile' Galaxy, which originally only had three 'Exterminator' Civilizations, welcomed a fourth civilization, or rather, a part of the fourth civilization.
Li Wenyuan used the coordinates provided by the 'Silent' to enter the galaxy directly using the warp drive. He did not interact with the 'cage' that sealed the galaxy.
Other than the 'Silent,' the other two civilizations in the galaxy did not realize that a new 'Outsider' had arrived.
Since the 'Silent' was also looking for something, Li Wenyuan simply disguised his spaceship after the 'Silent' model.
It was indeed difficult to disguise as a pure energy battleship. For example, one could discover clues by detecting the gravitational anomaly produced by the spaceship. In theory, the energy battleship of the 'Silent' had almost no mass, so the gravitational anomaly it could produce was very limited.