Hi, I was thinking that the OP can use a loop like the following to recursively check the embedded logical relations:

  $str = '( (1 == 1) and (2 < 1) ) or (2 > 0)';
  while ($str =~ s/(\([^()]+\))/$1/ee) {
    if (not eval($1)) {
       print "error: $1\n"; 
       last;
    }
  }
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or probably in another form:

  $str = '( (1 == 1) and (2 < 1) ) or (2 > 0)';
  while ($str =~ s/(\([^()]+\))/qq($1 || 0)/ee) {
       print eval($1) ? 'ok' : 'error';
       print ": $1\n";
  }
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which prints:

ok: (1 == 1)
error: (2 < 1)
error: ( 1 and 0 )
ok: (2 > 0)
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The problem is that it actually recursively checks every inner balanced parens even if they are after a success 'or' operator. i.e.

  $str = '( (1 == 1) or (2 < 1) ) and (2 > 0)';
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This is supposed to be a success pass, but it will return: (2 < 1) in my first code snippet which I think is not what OP wanted. Just some of my thought, might be useful for OP anyway.
Regards,
Xicheng