I just want to share how we can change Interface Language of Adapt Authoring Tool. I already changed the language into Chinese. Check the screenshot.
1. Go to folder routes\lang, there you can see 3 files: es.js, en.js and index.js.
2. Copy and paste en.js into the folder and rename it, in my case, I renamed it as cn.js.
3. Translate the file and after saving it, copy it to the folder called \temp\lang.
4. And now open index.js from the folder routes\lang and change the code at line 11
var lang = req.params.lang; to
var lang = 'cn';
5. Restart the server.
Note: 'cn' is the name of your language files, where you renamed at step 2.