my @temp = grep {$RE{net}{IPv6}{-sep=>':'}{-style=>'HeX'}} @$records;

I haven't tested it, but I think the  $RE{net}{IPv6}{-sep=>':'}{-style=>'HeX'} expression is just a Regexp object and needs, in this case, to be interpolated into an  m// operator:
    my @temp = grep { m/$RE{net}{IPv6}{-sep=>':'}{-style=>'HeX'}/ } @$records;
Or slightly more simply:
    my @temp = grep m/$RE{net}{IPv6}{-sep=>':'}{-style=>'HeX'}/, @$records;
In the second case, note the  m// is delimited by a  ,(comma).

Update: Or you could explicitly bind to the "topicalization" scalar  $_ with the  ~= operator (again, untested):
    my @temp = grep { $_ =~ $RE{net}{IPv6}{-sep=>':'}{-style=>'HeX'} } @$records;
or:
    my @temp = grep $_ =~ $RE{net}{IPv6}{-sep=>':'}{-style=>'HeX'}, @$records;