Validation message customization is ignored when property is a list

On a given scalar attribute configure a constraint rule, for instance regexp. Set up the form using at least this schema property. Use the recommended translation key to set up the message. Upload the corresponding key in the messages.properties file. Deploy. Test the constraint, message is correctly displayed. Go back to studio, set the field as multi-valued, change the corresponding widget. Deploy, test : message is back to displaying the regexp.