I would encourage you to look at the Perl CPAN module Unicode::LineBreak,
which fully implements tr11.  It includes Unicode::GCString, a class
that has a columns() method to determine the print columns.  This is very
fancy in the case of Asian widths, but of course there are many other cases too.

If you'd like, I can show you a program that uses these, a rewrite the
standard Unix fmt(1) filter that works properly on Unicode column widths.

--tom