Hi there,
Since BBP Style Pack is a third party plugin, we cannot provide any details why the customizations set using the plugin is not working due to the fact that there is simply no way to account for all of the potential variables at play when using another developer’s plugin or script. Because of this, any questions you have regarding setup, integration, or troubleshooting any piece of functionality that is not native to X will need to be directed to the original developer.
I checked your site as well and in the plugin settings, there is a tab that says Not Working? which has some suggestions you can check to troubleshoot your setup. It might help if you start from there then get in touch with the plugin author.
Currently, if you want to customize the display of the forum with X, you could override the bbPress template files then write some CSS codes. You can find more information about it here:
https://codex.bbpress.org/themes/amending-bbpress-templates/
Hope this helps.