If SGF text is not readable, problem is probably in unrecognized character set. Character set defines what (kinds of) characters can be stored in file.
If text is show as squares, problem is likely to be lack of proper fonts. Installing suitable fonts for language should solve problem.
GOWrite 2 versions 2.0.03 and later can read SGF files with any character encoding supported by Java Runtime Environment.
SUN Java Runtime Environment exists in two different versions: English and International. International version is bigger, but contains character sets for many more languages, like Japanese (SJIS).
Your operating system needs to support displaying the characters in the SGF file in order to show them correctly. Adding this support varies from Operating system to Operating system, please consult your platform's documentation on this.