Defining a network as trusted causes Firewall to create an internal bi-directional Allow rule with remote network criteria set to the trusted network. Any traffic to and from the trusted networks is allowed.
The Threat Event Log is a log file of all threat events that ePO - On-prem receives from managed systems.
In ePO - On-prem, you can define which events are forwarded to the ePO - On-prem server. To display the complete list of events in ePO - On-prem, select Menu → Configuration → Server Settings, select Event Filtering, then click Edit.
Set up a Purge Threat Event Log server task to purge the Threat Event Log periodically.
For information about Automatic Responses and working with the Threat Event Log, see the ePO - On-prem Help.