I have added:

change_parent_links_target=".fusion-text-2"

added to the shortcode, but the links still open in a new window. 

I just checked the demo. They work exactly how they should. In your case in example 10.  There are 2 links. 

"This example modifies the following two links. Link TWG features page and Link JFUploader page. They both don't have any target set. "

The normally would open in a new tab! And after the modification they open in the iframe. This is exactly what you ask for: Open links inside the iframe instead of opening like they do by default. 

Also I was on your page - the link targets are set and are working. So what is the problem still?

Best regards, Michael

Thanks! It's working now.

👍