Hi, Andy,
The built-in Menu can be edited to include/exclude specific slides. However, whatever settings you use apply to the entire course. In other words, you wouldn't be able to switch between settings for different languages.
Also, the built-in Text Labels (that is, the standard messages that appear, such as the warning that you need to answer a question before clicking the Submit button) can only use one language at a time.
That's why most folks I know use a separate Storyline file for each language. A good LMS should allow the user to select their preferred language and launch the appropriate course.
