This is a good discssion. The same points were raised earlier in a thread on gloriously foolish predictions.
From what I recall, RFC had left a post a couple of years ago, to the effect that the semaphore system generally did not work during the night, and during winter months either worked only 40% of the time or didn't work 40% of the time during daylight hours.
This was the state of the Church's semaphore system during non-war times. During wartime, especially in the north, the hard winter conditions, poor clothing, poor shelter (not necessarily in the towers, but everywhere else) and lack of supplies (in particular, food), along with personnel issues resulting from the Sword of Schueler, would create problems that very likely would impair the system even more..
Doubtless, communications (including staffing, fuel, food, etc.) would have a priority, but given conditions in the CoGA army faced in general, even with a priority, the signal towers would have been minimally staffed.
In those conditions, the odds of at least one tower in a chain being down temporarily due to illness, injury, frostbite, death from hypothermia, accident, etc. would be significantly increased. Couple that with the effects of weather and darkness on the system even in the best of conditions, and delays that would be, at least for a time, unexplained, likely would be common.
Finally, add in that no one in the CoGA or its Army even imagined the Charisan forces could be as mobile as they were in the winter. In these circumstances, even a couple of days' break in the chain, while meriting investigation, very likely would not cause alarm.
The key would be to take key stations out at night or during reduced visibility, so the profile to those other towers that are in sight is not changed during daylight hours. This buys both temporary invisibility for Charisan forces, and time.
This is the best I could come up with as a rational explanation. If the seijins also could give squads occupying the tower the proper "all is well" codes, it would work even better.
All the best,
X
