The vaults were scattered in different sections of the sea of destruction and the distance between them was surprisingly wide; if he were to measure it, he would say it was as wide as a thousand light-years across between him and the closest vault, the farthest ones were as far as millions of light years away, making Rowan wonder where this sea of destruction was truly located.
Transporting the Spirit Guises through the sea of darkness would be challenging, he could only send them across one at a time because of his limited consciousness power. He would need to physically move the Spirit Guises through the sea of destruction to assure their safety.
For an instant, he contemplated using a single Sovereign to transport the Spirit Guises to their destination, but that would defeat the purpose of his stealthy actions and reveal himself to the God King.