-- Outdated term? -- Speaking as an expert in reading ability and disability, I have not encountered the term "dysorthographia" to describe a disorder distinct from other types of language disturbances. Nor do I believe it is being used in either research, clinical or pedagogical settings. A Google Scholar search reveals no hits in the literature after about 1970. The definition provided here seems to suggest this disorder occurs in conjunction with either (developmental?) dyslexia or acquired aphasia following brain damage.
I suggest the article refers to a term that is no longer in use, and that it either be deleted or re-vamped to better explain that this is not a term currently in widespread use.