There are conventions that will facilitate faster testing. For example, if every translatable caption is fetched from a message catalog, you could merely check whether the message catalogs have been translated. (Different development environments use different terms for "message catalog", but hopefully the concept is clear.)
It is possible to tailor a UI framework so that developers are more likely to use message catalogs rather than hard-coded strings. In my experience, developers do not like to work with that kind of framework because they are forced to deal with internationalization before they want to.
Even if your developers use message catalogs consistently, there is no guarantee that the translated text will render appropriately on the page. For example, if a translated string is too long, it may wrap or truncate or impact the geometry of the page in undesirable ways. If a message contains application-supplied values, it is also possible that the values are supplied in the wrong order. For example, while the English error message might be:
File data.txt is missing from directory /home/Tester101
the Spanish error message might be:
/home/Tester101 archivo no se encuentra en el directorio data.txt
Ultimately, regardless of how the application was designed, there is no substitute for scrutinizing every page with your own eyes.