There’s a different component that provides a sensor.last_alexa which is used to respond back to the correct echo:
Regarding why nodered? Because more complex automations are 100x easier and faster to create. The screenshot below is a node red automation. If I ask Alexa, “Is the garage door open?”, alexa turns on the HA boolean. The automation then replies back to the amazon echo where I asked the question with one of four answers depending on whether one or both garage doors are open or closed. Creating this automation in HA took days and the help of more than 1 expert to get it right. I created it in node red in 10 minutes:
