This is why I propose something that can be heard or seen over long distances. As for your second question, I admit I do not know, which is why I do not suggest simply one system, but multiple systems that can work individually or in tandem. There are many unknowns in this village. The journal system could suddenly fail. Everyone could be rendered mute or deaf or blind. A shift could render everyone paralyzed. These are all possible realities and while we can prepare for the worst of things, we cannot plan for everything because we will always miss something. But you are right, even if we have systems in place, we should not rely entirely upon them in case something happens.

Beacons might work as well. We have watch towers around the village, if we have them properly staffed, they could be utilized in some fashion in case of an emergency.