typically we expose any localized text as optional properties and then inline the references - if you take a look at a file such as DesktopModules\CoreMessaging\view.ascx you'll see this with the plugin definition towards the bottom of the file.

Alternatively some modules do use ajax request's to pull localized value (I believe a few of the evoq modules do this),but care has to be taken to not end up with an extremely "chatty" application e.g. one that had dozens of localized text might work well with making multiple service requests in some areas (such as the US), but others such as Australia could perform badly because of network latency issues.