Hi, maybe you can snmp walkthrough by using mib browser and your device to check the accurate info details on the sensors.
You must check the correct OID for the device in order to get the sensors to get read.
As picture above, I am using MIB browser with MIB files specific for the device. From there you can know which MIBs file are using.
For the yaml discovery, you may check other os example.
File location /opt/librenms/includes/definitions/discovery/fiberhome-switch.yaml
Hope it works for you.