The idea is to create the menu system in the HTML block by hand. Here is how to do it quick and easy by just copying and pasting. Go to your forum and select the entire forum index menu from top to bottom. Do a copy, and it will copy the text AND the links. Now go to your page builders, open up the homepage and drag a new HTML block into place. Now while in the normal edit mode with the toolbars, paste in the text. It will automatically add the text AND links. Hit save and presto, you have a REAL forum index that is clickable on your Home page.
Sometimes the simple solutions are overlooked because we get caught up in the complex solutions.