Include specific stylesheet for specific language?
So you will probably need to remove the style sheet from your info file and add it in a pre-processor. 

I normally don't recommend using pre-processor functions but this is kind of the ideal exception to that rule. Checkout template_preprocess_html. In that hook you can pull the active language setting and conditionally add the language specific css file with drupal_add_css

function mytheme_preprocess_html()
{
  // Don't remember the code for this but you can figure that out.
  $language = getLanguage()

  if ($language == 'chinese_traditional')
  {
    drupal_add_css(drupal_get_path('theme', 'mytheme') . '/chinese.css');
  }
}


If the get language function uses a database call it would be better to do this in a custom module. DB calls in the theme are pretty much always a bad idea. You would in that case use the same code in hook_preprocess_page. At least that is what I was always told to do.