I just tried to register on your site with a different Facebook account to test with. First, there are a lot of fields to fill out during the registration process. I'd recommend using the Profile settings of JFBConnect and set the "Show Profile Fields" setting to "No" for a few of the systems you're integrating with. Right now, it's a long process to register.
When I did get the fields filled out and hit Register, the new user couldn't be created and the following error was thrown:
*** User forbidden. Please enable JavaScript. Check plugin setup. Request number 7fbeec0f48da876ba7333bbcef1844d7. Antispam service cleantalk.org. ***
I'm not sure what that means, but I tried a few times with the same results.
After trying with a new account, I logged in with the previous Facebook account I had created. The avatar still showed in the forums. I then edited my profile and removed my avatar so only the default was used. In the forum index, it showed the default, as expected.
Then, I logged out and logged in again with the Facebook account. My avatar was properly imported.
I'm not sure why you're not seeing the same behavior.
If you still can't get the avatar imported, please try to help determine why the registration process isn't working, or disable whatever spam extension you have enabled. Then, we can try with multiple different Facebook accounts to see if we can recreate the behavior with one of them.
Thanks,
Alex