$ perl -C -E 'my @x = ("\x{c5}de:Y", "Abc:X", "Afg:Z"); say for sort @x'
Abc:X
Afg:Z
Åde:Y

$ perl -MUnicode::Collate -C -E 'my @x = ("\x{c5}de:Y", "Abc:X", "Afg:Z"); say for Unicode::Collate->new->sort(@x)'
Abc:X
Åde:Y
Afg:Z