Add a string to file .pot using Poedit

Well, the way I work with Poedit is:

  • Open Poedit
  • Open the .pot file with Poedit
  • Define the language of the translation
  • Find the info you want to translate on the left collumn
  • Place the translation on the right collumn
  • Save the .po
  • Compile the .mo
  • Save both on the ‘language’ folder of the theme

Since you are trying to create a term where it doesn’t exists, the second line of your first step looks incorrect.

#: theme-name.php:123 // the reference
msgid "Page Title" // the original term
msgstr "" // the translation

Reference: https://developer.wordpress.org/themes/functionality/localization/