I sent it from the web client and it displays just fine to me. This is what I recieve:
@color=#1E90FF;emotes=25:0-4,8-12;subscriber=0;turbo=0;user_type= :livewhiletrue!livewhiletrue@livewhiletrue.tmi.twitch.tv PRIVMSG #livewhiletrue :Kappa 𠜎 Kappa
This is as read from UTF-8 encoded console output on Eclipse Luna.
I also tested letting my bot echo whatever I typed and recieved the same error as you when posting “Kappa 𠜎 Kappa”
Interestingly, when only posting “𠜎”, I also receive this message:
TMI.js [irc] WARNING: Invalid emotes tag:
TMI.js [irc] ERROR: Failed parsing IRC message @color=;emotes=;subscriber=0;turbo=0;user_type=mod :mybot!mybot@mybot.tmi.twitch.tv PRIVMSG #livewhiletrue :𠜎
On second thought I think this could be helped by changing the outgoing encoding (just new to all these things, and learning as I go)
edit: for those who want to test their applications I got the test characters from here: http://www.i18nguy.com/unicode/supplementary-test.html