Localize the token value

Here's an alternative: use Language Sections → as part of the input filter that you use to define custom tokens. I prefer this approach because the standard Drupal string localization route has two significant disadvantages for me:

* You must remember never to change the original English or default-language text - if you do you will lose the translations.
* The string localization UI is difficult to use, especially for inexperienced users. The Language Sections approach is not perfect either, but better in this case I think.