> I would encourage you to look at the Perl CPAN module Unicode::LineBreak,
> which fully implements tr11.

Thanks for the pointer!

> 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.

I believe there can't be any truly "proper" implementation, as you
can't be certain how the terminal will handle these itself. In any
case, anybody who is interested in contributing a patch should also
be capable of understanding the source of Unicode::LineBreak.