Hmmm, very tricky without analysing your server set up and the code. It appears that for some reason, the labels for the localization of the API are not being downloaded. Here are a series of suggestions.(of increasing difficulty)
1) Try loading the basic example with components here, and see if it causes you the same error. A copy of this example can be used as a basis for further discussion
and removes any doubt as to where the issue lies.
2) Try making a local copy of the "basic example with components " example and see what happens when accessed as a local file and when hosted on your server.
3) Try forcing the language to German say, by adding the following line after your app id and token:
4) Open the example localhost and on the server in Google Chrome , press F12 to open the debugger and press the Scripts tab then reload the page, you should see a language-en-US.js script being loaded. This holds the missing texts.
For each of these ensure that the local cache has been cleared so that there aren't any side effects from residual code.
If for some reason your server or a proxy is blocking the language-en-US.js script then this is potentially the cause of your problem.