Currently, the Goals field is not supported for Automation actions such as copying the Goals value from one issue and adding it to another. The Goals field is not selectable and even when using the advanced field editing, the value is not copied over to another issue even though the rule is correctly triggered.

{
  "fields": {
    "Goals": "{{triggerIssue.goals}}"
  }
}

It also doesn't work passing the ID directly to the Goals field.