The spamassassin configuration has to be changed to change the language settings. For that you can edit the file user_prefs located at /home/username/.spamassassin if it isn’t located there you need to create one.
We need to edit or add values ok_languages with the extra languages you would like to have in the two letter code.
This option is used to specify which languages are considered OK for incoming mail.
ok_languages all (allow all languages)
ok_languages en (only allow English)
ok_languages en ja hi (allow English, Japanese, and Hindi)