my $string = 't?e\\\\xt\\\\* with escapes\\*';

my $result = '';
for ($string) {
    /\G \\(.) /xgcs && do { $result .= $1;   redo; };
    /\G \*    /xgcs && do { $result .= '?';  redo; };
    /\G \?    /xgcs && do { $result .= '#';  redo; };
    /\G (.)   /xgcs && do { $result .= $1;   redo; };
}

print($result, "\n");