This affects both 3.4.0 and r1765:
If a user quits, then a quit message is displayed to the remaining user in the language the quitting user has setup. So if the user who is leaving has setup her game language to be portuguese, but the other users have different languages setup, such as english and french, the other users will still get to see this message about the user quitting:
Username: Decidiu sair do jogo!
It seems that some client messages are just passed through as localized strings, not as placeholders which then get translated by each receiving users' game. This would also explain why sometimes you get to see something like ???QuitGame??? when a user quits who doesn't have up to date language files (but you do have up to date ones).