Some of the strings are translatable like: Viewed, Past:

But I cannot seem to find those strings to translate: 1 day, 1 week, 1 month, 1 year, (X times)

Comments

yngens’s picture

yngens commented

The main problem is that per /admin/config/mostpopular/intervals the module needs strings which can be understood by strtotime(). Which is a matter of bad design as every single string in Drupal UI should be translatable. I second the request to make these strings available for internationalization.