Possible to automatically create forum topic when user submits review on Wordpress theme?

If a review is a WordPress post-type then it may be possible. If you have the WP Discourse plugin installed on the site, go to the bottom of the plugin’s Publishing options tab and look at the ‘Post Types to Publish’ section. Do you see a post-type listed in that section for reviews?

What WordPress plugin are you using for reviews? If it’s a free plugin, I’ll take a look at it.