The Sigils of Listening would temporarily solve the challenges of transmitting long-distance messages. Although they were scarce and could only be used by witches, they were still better than entirely depending on a carrier pigeon.
The Sigil of Screaming tweeted at a high pitch when it sensed demon power and it also effectively suppressed any of the enemies' sneak attacks and the area of coverage was about the size of the Border Area.
The Sigil of Observing could assist with Thunder's adventure plan. It would be a pity for Roland to miss the spectacular and strange sealine since he was unable to follow the fleet out to sea.