Support of Unicode is simply not in yet. Ideally it would unify all the different approaches used in C code.
But the discussion on what to include (eg. only UTF-8, etc) is a tricky one that has no neat solution i fear.
UTF is not in yet, because C2's goal domain is embedded drivers/kernels/operating systems, etc. There UTF
is not really important as in a generic systems language.
But I haven't really looked into a proper UTF solution yet. On the web, UTF-8 is definately dominating.