Patches Y.Intl.get to use the language bundles produced by locator-lang plugin, and will be available thru locator's bundle objects on the server side. You can apply this patch like this:

app.yui.patchServer(require('express-yui/lib/patches/server-intl-get'));

Then you can use this in your program:

Y.Intl.get('<bundleName>/foo');

This will resolve foo as a language bundle from the bundle specified by name, which is normally a file in lang/foo.json or lang/foo.yrb that was transpiled into a module by locator-lang.