If you like to change some translations inside Freelance Cockpit you can just create a file named custom_lang.php inside your language folder i.e. /application/language/english/custom_lang.php and add new language lines or just overwrite existing ones like below:
<?php
/* Add your custom language lines here! You can also overwrite existing language lines. */
$lang['application_subscriptions'] = "Contracts"; # Change Subscriptions to Contracts