As an update I now released Perl6::Str on CPAN. It allows you to work with strings on the grapheme level, like this:

use Perl6::Str;
use charnames qw(:full);
my $str = Perl6::Str->new("A\N{COMBINING DIAERESIS}O");
print $str->reverse; # will print OÄ, as is DWIMmy.
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