## ... %tags as defined in the OP ...

my $tagcnt = scalar keys %tags;  # let's be sure about how many tags there are

warn scalar localtime(), $/;   # initial time mark

my $prev_codepoint = 0;
my @outrec;
my $ndone = 0;

while (<>) {
    next if /^#/;       # skip comments
    chomp;
    my ($codepoint, $tag, $content)     = split /\t/;
    $codepoint  =~ s/^U\+//;            # replace U+ with 0x
    $codepoint  = hex $codepoint;       # treat 0x number as hex, convert to dec
    if ( $codepoint != $prev_codepoint ) {
        printrec( $prev_codepoint, \@outrec ) if ( $prev_codepoint );
        @outrec = map { '' } (1..$tagcnt);
        $prev_codepoint = $codepoint;
    }
    $outrec[$tags{$tag}] = $content;

# ongoing time-stamping:
    warn "$ndone done at ".scalar localtime()."\n" if ( ++$ndone % 1000 == 0 );
}
printrec( $prev_codepoint, \@outrec );

warn scalar localtime(), $/;  # final timestamp

sub printrec {
    my ( $cp, $rec ) = @_;

    my $s = join( "\t", $cp, @$rec ) . "\n";

    $s  =~ s/([\x{10000}-\x{1FFFFF}])/'\x{'.(sprintf '%X', ord $1).'}'/ge;

    print $s;
};