c:\@Work\Perl\monks>perl -wMstrict -le
"use Data::Dumper;
 ;;
 use constant SENTENCE => 'this word word (word) is a word';
 ;;
 my %dic = (
   'word word' => 'parola parola',
   'word'      => 'XXXX',
   '(word)'    => '(parola)',
   );
 print Dumper \%dic;
 ;;
 print '---------------';
 ;;
 my ($rx_A) =
   map  qr{ (?<!\w) (?: $_) (?=\s|$) }xms,
   join ' | ',
   map  quotemeta,
   sort { length $a <=> length $b }
   keys %dic
   ;
 print qq{rx_A: $rx_A};
 ;;
 my $s = SENTENCE;
 print qq{'$s'};
 $s =~ s/($rx_A)/$dic{$1}/g;
 print qq{'$s'};
 ;;
 print '---------------';
 ;;
 my ($rx_D) =
   map  qr{ (?<!\w) (?: $_) (?=\s|$) }xms,
   join ' | ',
   map  quotemeta,
   reverse sort { length $a <=> length $b }
   keys %dic
   ;
 print qq{rx_D: $rx_D};
 ;;
 $s = SENTENCE;
 print qq{'$s'};
 $s =~ s/($rx_D)/$dic{$1}/g;
 print qq{'$s'};
"
$VAR1 = {
          '(word)' => '(parola)',
          'word' => 'XXXX',
          'word word' => 'parola parola'
        };

---------------
rx_A: (?^msx: (?<!\w) (?: word | \(word\) | word\ word) (?=\s|$) )
'this word word (word) is a word'
'this XXXX XXXX (parola) is a XXXX'
---------------
rx_D: (?^msx: (?<!\w) (?: word\ word | \(word\) | word) (?=\s|$) )
'this word word (word) is a word'
'this parola parola (parola) is a XXXX'