I can't seem reproduce this issue here. I joined irc.unilang.org and used the same nick (as well as other utf-8 nicks) and then joined a channel. The nick appeared correct in both the status window and the channel window nick list. Are you sure that the channel window you joined is set to display utf-8 in the fonts dialogs? If you send messages to the channel, does your nick appear correct in the channel window message?
