You can extend Enterprise Risk Report according to your business needs. Enterprise Risk Report has extensibility in the form of custom fields which are implemented in the various SAP Risk Management Fiori apps.
You can add custom fields to the risk entity (Refer to SAP note 1470670 - Adding User-Defined Fields to Risk Management 2010). The fields added will appear without additional customizing in the app.
To hide certain fields from the app, you can maintain the visible fields in IMG as outlined below:
Navigate to Governance, Risk and Compliance
Navigate to Reporting
Navigate to Smart reports
Navigate to Maintain Visible User-Defined Fields
For a general description of the extensibility options and procedures of SAP Fiori apps, see http://help.sap.com/fiori_implementation .