The following hack seems to work:

#!/usr/bin/perl -w
use strict;

use File::Tail;
use IO::Handle;
use Encode;
#use Devel::Peek;

my $scan_log_file = "foo.u16";

unless (fork) {
    # emulate Windows file for testing
    open my $fh, ">:encoding(UTF-16le):crlf", $scan_log_file or die $!
+;
    $fh->autoflush(1);
    
    for (1..5) {
        print $fh "foo bar\n";
        sleep 1;
    }
    print $fh "finished\n";
    exit;
    
} else {
    sleep 1;
    
    my $o_tail=File::Tail->new( 
        name               =>  $scan_log_file, 
        maxinterval        =>  1, 
        adjustafter        =>  1, 
        ignore_nonexistant =>  1, 
        reset_tail         => -1,
        tail               => -1,
    );

    while( my $line = $o_tail->read() )
    {
        $line =~ s/^\0//;  # fix possible char misalignment
        $line = decode("UTF-16le", $line);
        $line =~ s/\r$//;  # remove \r
            
        #Dump $line;
        print "$line\n";
        
        if( $line =~ m/finished/ )
        {
            print "done.\n";
            last;
        }
    }
}
[download]