I went a different route. Basically I changed the input record separator to grab the 'BS' and then restore the input record separator to its default value.

After that, I process the data line by line again. Here's my code. 
#!/usr/bin/perl

use strict;

local $/ = "QE)";
my %hash;
while (<DATA>) {
    s/BS:\s(\w+).*QE\)//;
    $hash{'BS'} = $1;
    do {
        local $/ = "\n";
        s/(\w+) \((\d)\% \/ (\d) of \d+ \| event (\d)\% \/ (\d) of \d+
+\)//;
        print "$hash{'BS'}\t$1\t$2%\t$3\t$4%\t$5\n" if ( defined($2) )
+;
    }
}


__DATA__
AAA_AA1_DDD (0% / 0 of 1024 | event 0% / 0 of 1024)
AAA_AA2_DDD (0% / 0 of 1024 | event 0% / 0 of 1024)
BS: 111_DDD, QE: QQQ_DDD (additionnal QE)
BBB_BB1_DDD (0% / 0 of 1024 | event 0% / 0 of 1024)
BBB_BB2_DDD (0% / 0 of 1024 | event 0% / 0 of 1024)
BS: 222_DDD, QE: QQQ_DDD (additionnal QE)
CCC_CC1_DDD (0% / 0 of 1024 | event 0% / 0 of 1024)
CCC_CC2_DDD (0% / 0 of 1024 | event 0% / 0 of 1024)
BS: 333_DDD, QE: QQQ_DDD (additionnal QE)

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In reply to Re: Plan of Attack. by bichonfrise74
in thread Plan of Attack. by NothingInCommon

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