The current mechanism for specifying a global i18n resource bundle is not very flexible.
It requires you to name your i18n bundles the same as your .application file. Furthermore, it requires that your bundles be places in the WEB-INF directory. Most other web frameworks (and Java applications in general) require you to have the ResourceBundle somewhere in your classpath (generally in the root - WEB-INF/classes).
1. I think the root of the classpath should be the default location - even if you're using the ".application name matches i18n name" mechanism.
2. It should be possible to customize the name of the file. Possibly something like the following in your .application file:
<property name="org.apache.tapestry.global-properties" value="ApplicationResources"/> -> points to WEB-INF/classes/ApplicationResources.properties (and others with _locale.properties
<property name="org.apache.tapestry.global-properties" value="com.myapplication.web.messages"/> - points to /WEB-INF/classes/com/myapplication/web/messages.properties