If understand it correctly, one possible issue is that this can’t learn long sequences because it is feedforward only. It might only be able to learn sequences one transition long per level of the hierarchy.
How would it represent ambiguity, where it doesn’t know the sequence context for a currently active SP cell?
As far as I know, cells are only inhibitory or excitatory, but this would require cells to be both or it would require intermediate inhibitory cells with specific targets and hebbian learning, which might not exist between levels of the hierarchy.
Maybe some sort of gradient between core/peripheral cells would help, because how closely two things correlate is on a gradient.