There's probably a better way to do it, but you could do something along the lines of:

my %test;
$test{a}{b}{c}{d} = "Hi";
my @keys = qw( a b c d );
my $out;
my $ref = \%test;
for( @keys ){
  if( ref $ref->{$_} eq 'HASH' ){
    $ref = \%{$ref->{$_}};
  }
  else{
    $out = $ref->{$_};
  }
}
print "$out\n";
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