Try the 4.0.1 attachment... You shouldn't need to make any changes as CKEditor automatically localizes to the user language if none is specified in the config file.
I downloaded and installed/tested version 4.0.1 and the editor does not show up. Same with version 3.6. The only version which are showing up are version 3.5 and 4.0.
Then I reinstalled the complete couch cms - same result.