ROADBOOK CREATOR currently supports 3 languages: French, English, German.
It is quite possible to create your own language file.
To add a new language to the list, go to the file reglages.php then edit the variable $ langages_liste . For example if you want to add Spanish:
public $langages_liste = array ('Français' => 'fr_FR', 'English' => 'en_EN', 'Deutch' => 'de_DE', 'Español' => 'sp_SP');
Example for Spanish:
Once the language is implemented, all that remains is to create the files. Duplicate the file of your choice (JS and PHP) then rename them to sp_SP.js and sp_SP.php All that remains is to modify the values to be translated.