We haven't tested with jReviews as much recently as we would have liked. Their previous releases worked very well with JFBConnect, and I believe the current ones still do as well. We have a subscription to their extension and are also planning some integration between the two coming up, but I just don't have the answer you're looking for right now. What I would recommend is:
1) Enable the Like / Share button but leave the API / Secret key blank. Test if the button shows. If so, then try to open the source code / HTML on the page and search for "all.js". If it only is in there once, from JFBConnect, everything should be good.
2) If that doesn't work, add the API / Secret key. Check the HTML again and see if 'all.js' is there twice.
If the all.js file is in twice, that's bad and can cause issues. If you only see it once, and the buttons work, everything should be great.
Hope that helps. If not, let us know. Again, we're planning to add jReviews to our test suite and work a lot closer with them, but just don't have any good answers now.
Thanks,
Alex