Can you go to the JIRA ticket and attach two screenshots showing the effects of your changes? One for long and another for short.

The logic for which format to use should not be in the jsp, but rather in the PersonName class.
Can you do the following:

1. Add a static private field to the PersonName class. You could call it "format". Initialize it with the value that the global property starts with.
2. Add a public static setter like "setFormat()"
3. Register a GlobalPropertyListener which calls PersonName.setFormat() when the property changes. For an example of this you can look at classes like GlobalLocaleList, WebUtil, etc. Remember to register this listener in applicationContext-service.xml under bean id="openmrsEventListeners"