To support languages other than English, you can encode your inputs with base64 encoding before calling the APIs.
For calling SaveUserScore
ScoreBoardService *scoreBoardService = App42API::BuildScoreBoardService();
int score = 400;
string userName = "汉语";
string userN = base64_encode((unsigned char const*)userName.c_str(), userName.length());
scoreBoardService->SaveUserScore(gameName, userN.c_str(), score, this, app42callfuncND_selector(TestScoreboardService::onScoreBoardRequestCompleted));
When you receive response
string userName = base64_decode(app42Score->getUserName());
The encoding and decoding methods are available in the SDK in class "app42base64.h" but you need to include this class where you want to use these methods, or you can use the base64 class provided by Cocos2d-X.
I hope it will help.