Steps to reproduce:

1. Create Connector as described here: https://git.zabbix.com/projects/ZT/repos/receiver/browse

• Install git and golang

  dnf -y install golang git
  

• Create and move into directory /usr/lib/zabbix/connectors
• Clone the repo with connector and move to the connector directory
• Set port in connector config.json to 8080
• Run command:

  go build
  

• start the connector:

  ./Example_interface &
  

1. Create Host with macro as on screenshots:
   
   

1. Create Item as on the screenshots:
   
   

1. Create connector as on the screenshot:
   

Result:
If you check file:

tail -f /usr/lib/zabbix/connectors/receiver/data/history.ndjson

you will find that host macro used in item name will not be resolved (File {$FILE_NAME} exists):

{"host":{"host":"Connector test","name":"Connector test"},"groups":["test"],"item_tags":[{"tag":"transmitted","value":"connector"}],"itemid":57554,"name":"File {$FILE_NAME} exists","clock":1774254184,"ns":725638653,"value":1,"type":3}

Expected behaviour
The macro will be resolved.