Hi,
I’m also starting to use espresense but I think I found an easier way 
I added a channel to my broker to get all MQTT updates in the devices topic for a special device:
“14_Pro_Max” is my in the espresense configured and monitored iPhone. With the “#” I receive alle keys and values for handling later in a rule.
After that I created a dummy String item for visualising the room name.
I created following rule to check for the room name and set it the previous created dummy String item:
var klausLastRoom = ""
var klausLastDistance = 10.0
rule "espresense_room_klaus"
when
Channel "mqtt:broker:Matt_broker:c_14" triggered
then
val json = receivedEvent.split('#').get(1)
val distance = transform("JSONPATH", "$.distance", json)
val distanceDouble = Double.parseDouble(distance)
val room = receivedEvent.split('#').get(0).split('/').get(3)
//checking if the room is the same current
if(klausLastRoom != room){
logInfo("espresense_log", "Checking new room: " + room)
//checking if new room is closer than current one
if(distanceDouble < klausLastDistance){
klausLastRoom = room
klausLastDistance = distanceDouble
// translating the technical espresense names to human readable ones (hard coded)
if(klausLastRoom == "esp_og_eltern"){
iphone14Room.sendCommand("Schlafzimmer")
}else if(klausLastRoom == "esp_eg_living_room"){
iphone14Room.sendCommand("Wohnbereich")
}else if(klausLastRoom == "esp_ug_office"){
iphone14Room.sendCommand("Büro")
}else if(klausLastRoom == "esp_ug_cellar"){
iphone14Room.sendCommand("Keller")
}else{
iphone14Room.sendCommand("Unbekannter Raum")
}
logInfo("espresense_log", "New room for device detected: " + room)
}else{
logInfo("espresense_log", "Room ist too far away: " + room + ". Current distance is " + klausLastDistance + " vs. " + distanceDouble)
}
// update distance for current room
}else{
logInfo("espresense_log", "Current room info for: " + room)
klausLastDistance = distanceDouble
logInfo("espresense_log", "Updated distance for current room: " + klausLastDistance)
}
end
For other devices a new channel for the broker, a new dummy String item and a new rule is needed (easy copy paste modify)
Hope it helps and saves you some time