Graham tiaxgame  
Ok I have found a solution and I am also giving you a whole new toy to play with
You need to install the guestbooks twig file

1/ create a folder named _xtgem_templates
2/ create a plain text file named xtguestbook.twig in _xtgem_templates
3/ go to this page and copy the code for the twig file to xtguestbook.twig
Open and edit with code editor only
4/ in the xtguestbook.twig file find line 49
<div class="xt_blog_comment_content">{{ comment.message|raw }}</div>
5/ replace that line with
<div class="xt_blog_comment_content">{{ comment.message|replace({'(': "&#40;", ')': "&#41;"})|raw }}</div>

The documentation for twig is at http://twig.sensiolabs.org/doc/templates.html

This will replace ( and ) in posts with &#40; and &#41;

There is also a twig file for the blog this goes in the same folder and is named xtblog.twig
The code is at
https://dl.dropboxusercontent.com/u/2162515/xtgem_blog.twig

have fun
test page http://guestbook.yn.lt