Yup.. Now you know the 'core' of JFBConnect should work. Disabling the sh404SEF plugin was a great find, and something the Error Check tool is meant to help root out.
Now, the next steps are to re-enable any optimizations you want and test JFBConnect however you want to use it. If you do run into any functional issues, try disabling the optimizations to see if they go away. That can help localize the problem to the optimizations or to JFBConnect itself.
Any issues you run into, just let us know about, and we'll help however we can.
Thanks,
Alex