The text fields in the Kursinfo can be edited with "Beschreibung ändern". Changes can be saved and it seems that they are stored (e.g. Author or Kennzeichen). But it is not possible to delete the text entries. After delete and save the text fields are empty, but after refreshing or click to another page and back to the Kursinfo, the previous value is visible.
RepositoryManager.setDescriptionAndName() does not allow to store empty strings. See comment.