The information on the OTA API is located at https://admhelp.microfocus.com/alm/en/12.53/api_refs/ota/webframe.html (this is for 12.53 but should work)
The information on how alerts work in the User Guide is in Chapter 4 starting on page 113
The information on how alerts work in the Admin Guide is in Chapter 20 starting on page 301
When using the alerts there is not really any options that can be changed from what is listed in the project customization. The Alerts also rely on tests being linked to the defects. Usually the the alerts are flagged in the UI and an email is sent to the responsible tester (if the defect status) or the Assigned to user if the test status changes to passed).
You could possibly use the workflow to modify the behavior of alerts. You would probably need to set something up where on post specified fields were evaluated and then the workflow generated alerts to the required users or groups.