Hi! Yes, the option is correcty settled. To add images, we use a WYSIWYG editor called JCE. but this editor does not add anything rather than <img> on article's HTML.
There are lots of components and plugins working on the portal (as many Joomla websites), but other <meta descriptions> that Your extension pass (such as url, and title) are correctly interpreted by Facebook. Only issue the image.
Maybe you can take a look to the links I sent you in PVT, i can provide you full admin access to the website if needed.
I absolutely need that functions of "og:image auto-compile", as our is a blog news, I cannot overlay with a simple general image, and sometimes people that write articles aren't so good with html.

)
Thanks for support, Antonio
PS in the meanwhile I will try to play with plugin orders, who knows...thanks!