Hi info19,
You need to create a .po and .mo file to translate the language. If you directly customise the code then while updating to our new version all your customisation code will be lost and you need to do each and every time while you update the theme.
The file is inside attitude -> library -> structure -> content-extension.php on line no 156, 329, 488, 603 and 720
If you customise the code then first make child theme and then only customise the code.
Thank you!