I have a site that uses non-latin characters in URLs, e.g. http://example.com/drupal/новости. When the URL is copy-pasted, some browsers change the URL to http://example.com/drupal/%ED%EE%E2%EE%F1%F2%E8, and this causes an Page not found error.
Consider trying the Transliteration module. Here is a quote from its project page:
... it takes Unicode text and tries to represent it in US-ASCII characters (universally displayable, unaccented characters) by attempting to transliterate the pronunciation expressed by the text in some other writing system to Roman letters.
As a sample, it transforms an URL like
mydomain.com/последние-новости-в-Украине-и-мире in something like
Other modules that might help to solve this question: