As it stands currently UpdatePlayerStatisticsResult returns nothing. Due to the nature of Leaderboards in PlayFab a successful score update doesn't' necessarily mean the player will now have that score for the leaderboard.
It would be really great to get the actual score of the player on the specified leaderboard after the score was posted returned on success.
To give a quick example of expected behavior.
1. Leaderboard created with highest score only type.
2. Score successfully posted to leaderboard for player.
3. Score posted lower then current score for specified leaderboard.
4. Return highest score for leaderboard ( in this example that would not be the score posted in the call )
Hope this makes sense. Thanks in advance!