def METHOD_NAME(self):
    for lang_code in self.languages:
        if lang_code in self.data:
            for fieldname in self.translated_fields:
                identifier = self._get_identifier(lang_code, fieldname[0])
                data = self.cleaned_data
                if identifier not in data or not data[identifier]:
                    msg = 'This field is required'
                    raise ValidationError((identifier, msg))
    return self.cleaned_data