Note that in order to get the formatting, you need to cache the previous string in order to determine the indentation.

#!/usr/bin/perl
use strict;
use warnings;
use Text::CSV;

#my $file = "fielded.txt";

my $csv = Text::CSV->new({sep_char => "\t"});     # create a new objec
+t
open my $fh, "<", $file or die "Unable to open $file: $!";

my($u_value, $p_value, $mc_value) = (undef) x 3;
while (my $data_ref = $csv->getline($fh)) {
    my @data = @{$data_ref};
    if ($data[0] eq "'EOU'.") {
        ($u_value, $p_value, $mc_value) = (undef) x 3;
        print "\n";
    } elsif ($data[2] eq "u") {
        $u_value = $data[3];
        print "\n$u_value";
        undef $p_value;
    } elsif ($data[2] eq "p") {
        if ($p_value) {
            print "\n" . ' ' x length $u_value;
        }
        $p_value = $data[3];
        print "\t$p_value";
        undef $mc_value;
    } elsif ($data[2] eq "mc") {
        if ($mc_value) {
            print "\n" . ' ' x length $p_value;
        }
        $mc_value = join("\t",@data[7 .. 11]);
        print "\t$mc_value";
    } else {
        #die "Unexpected line format encountered, $file, @data";
    }
}
close $fh;
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