http://bugs.winehq.org/show_bug.cgi?id=36377
--- Comment #8 from Will Temple willmtemple@gmail.com --- IMEConfig.xml missing is interesting at least. Search for the error shows that this is common behavior in League on Windows particularly in non-english-speaking locales and has to do with alternate Input Method Editors for different locales in Windows. The file is not existent on my machine.
I can confirm that the problem is nonexistent when the Windows version is set to Windows XP.