Usually when loading a level in the campaign there is the possibility to change the language you want to use, by choosing change hero and clicking on the dropdown menu for languages. See also: How do I change the programming language?
However, in the level zero-sum in the Cloudrip Mountain, you do not play with your own hero and equipment. The play button takes you directly to the level and there is no possibility to click on the change hero button.
Is there another way to change the language? Am I missing something or should this be fixed?