I guess you tested different children config, thus got child ids mixed. IMO it needs to either delete this node in mysensors.json or delete the file itself to force homeassistant to refresh this node with all children.

Just checked the solution: 9 hours of calm ghostless sleep. :)
At lat I've got solid setup for PIR sensor. It was a headache for me last 6 months, when I tried it with ESP8266