What still needs to be understood about the 2/3 layer of the neocortex?

Jeff Hawkins states, in this video/presentation, that, according to him, “we” (I suppose, “we”, the humans) understand about 98% of the 2/3 layer, where, according to the HTM theory, high-order inference occurs. Why 98%? Please, answer this question only if you’re Jeff Hawkins or you have a very good understanding of the HTM and neuroscience. (Note: I have almost no knowledge of neuroscience, so keep that in mind, but be rigorous.)

He also says that there are a few things that need to be reviewed and cleaned up. What are these things?

I suppose that the estimate may have changed meanwhile. If you’re very qualified to answer this question about the new estimates, new updates about our knowledge regarding this 2/3 layer, then you can answer.

Please, no speculation. Answer only if you’re really qualified to answer my questions. And, please, stay on topic!!