my %data_h = (previously calculated data);
my @errors;  # store errors here
my @passed;  # list items that passed the tests
foreach (@list) {
   if ($condition{'a'} == 1) {
   # perform test A on $_ using data from %data_h
   # if it fails, add an error message and go on to
   # the next list item
   }
   if ($condition{'b'} == 1) {
   # perform test B on $_ using data from %data_h
   # if it fails, add an error message and go on to
   # the next list item
   }
   # and so on, with several other tests

   # if it survives all these tests...
   push @passed, $_;
}

if (@passed) {
# etc.