おはようございます。

my @values = qw[(A)B B(A) (C)B(A) B(C)(A) A B(C(A)DEF BC(D(A)))E) BC(A)(D B)C(D(AAA)(E(FG BC(A)()];

for my $value (@values) {
my @hits = $value =~ /\(([^\(\)]*)\)/g;
print "$value = ",$hits[$#hits],"\n";
}

(A)B = A
B(A) = A
(C)B(A) = A
B(C)(A) = A
A =
B(C(A)DEF = A
BC(D(A)))E) = A
BC(A)(D = A
B)C(D(AAA)(E(FG = AAA
BC(A)() =

…こういう感じであってますか？