It isn't quite clear to me what you want to achieve.

With the template you posted you shouldn't get anything else then the contents of the Comment header in your message body, so that is as it should be.
Though you're using a rather complicated way to retrieve the contents of that header, you can insert the contents of any header with the %Header("header name") macro, in this case that would be be: %Header("Comment")
As the Comment header is a special case, you could also use %Comment

Your complaint is that this is the only thing in the message body, there's nothing more that you specified.
In case you want the full original message text in the body, you should add the %Text macro to your template.
In case you don't want the full text, you should be more specific.

The To: header should be the addressee that you set in the action properties, the %Subject should be added automatically.

But let's start this systematically. What are the contents you want in your new message nand why?

OK, I get it.

But there should be no reason at all to omitt the dashes at the end of the line, the %- macro skips the empty line that's caused by the fact that the macros in front of it leave no text in the message body.

Your %FromAddr macro isn't necessary, it only inserts your own address in the message body and I presume that you know that.

The %Subject="BlogPost" should do the trick with regard to the subject, but it'll add a new empty line to your message body, so you'd better follow it up with a %- macro.
Your %To= macro is messing things up. Because you define the addressee in the forwarding action of the filter action, the defined address should be added to the primary addressee. Unfortunately these templates aren't executed in one run and that means that some macros and filter actions properties are interpreted more than once.
Presumably you've left the addressee in the filer action blank and that's the property that is winning out. So you should skip the %To= macro and define the addressee in the filter action properties.
The same mishmash could be happening with the subject, but we use a different procedure for that. We set that header to be modified only once, that's to be done with the %ModifyOnce macro.
So basically I'd advise this template:

%SetPattRegExp="(?is)(.*?)Comment:\s\n(.*?)\n"%-
%RegExpBlindMatch="%Text"%-
%SubPatt="2"
%ModifyOnce("Subject")%-
%Subject="BlogPost"%-

Good luck.

Closed the bat and restarted it..... All is working now! thanks!