Most "text" files nowadays are actually unicode, 16-bit files ("wide" characters).
Running these through LanguageTool produces garbage, like
Message: This sentence does not start with an uppercase letter
... â€œNo.â€? ...
Do you know any command-line tools for doing the most-common conversions (e.g., left and right quotation marks to quotation marks, long dash to dash, the "..." character to "...", stupid stuff like that)?