Previously i just try to check your site and try to make the changes as your request on above. But it seems it won’t affect the front-end website and i notice you’re using Cloudflare. Can you please try to clear the cache on Cloudflare to see the change results? Let us know if it’s work or not.
Previously i just make small changes and it’s not finished yet and then i ask you that if you use Cloudflare on your site you may need to clear the cache because the changes on customizer don’t work on the frontend. I just check your site and it seems you’ve been making several changes in there, do you need further help? just want to make sure.
In order to add custom metadata on certain page or post, you may need to do some changes to the theme file. Maybe you can try using ACF plugin to make custom metadata field on your custom post type but you may need to do some changes in order to show the metadata on frontpage display.