For older versions of Perl (<= 5.8.8), you'd need an additional :utf8 layer at the end, i.e. :raw:perlio:encoding(UTF-16LE):crlf:utf8 (although this isn't needed with newer versions, it doesn't do any harm either)
So do the cognoscenti of the Perl community agree then? The canonical workaround to the Perl UTF-16-on-Windows defect is to use the following sequence of layers in the three-argument form of open for both input (<) and output (>).
open my $input_fh,
or die "Can't open input file $input_file: $OS_ERROR\n";
open my $output_fh,
or die "Can't open output file $output_file: $OS_ERROR\n";
I think this only goes to prove your point that this is way too arcane for mere mortals... And, even though there is a "solution" to the issue, the current behavior of the :crlf layer is definitely a bug, IMHO. For one, it violates the principle of least surprise. Instead, the following straightforward approach (as anyone sane in his mind would glean from the existing documentation) should work: open my $fh, '<:encoding(UTF-16LE)', ...
Thank you! That's all I'm saying.