One way you could go about this is by using the #is helper to check the name of the dropdown item language, and display the name and flag based on the result. Here's an example of how that could look:
You'll need to add the flags as assets in your help center and update the file path in the assets helper. You'll also need to add some custom CSS to the language-item class in order to have the flag image appearing similar to the screenshot above.
Sorry I'm not quite following what you're hoping to do. Would you mind going in to more detail about what you'd like to see?
Thanks!
Tipene