I've added the inverters on mine. Immediately before PIC one each on clk and data.
Same as clock buffer - NL27WZ14.
But even before that I was getting much better error rates. I consider 3-5% to be bad enough and on my notebook without hub that's what I get. The hub doesn't do as well as the RaspPi though. It consistently gets <1%.

The new board revision has both Dual NOR gate and inverters, I've completed it now except for adding beads on the USB signals. I worked all night on the ferrite beads on the ASICs, moving the PIC to make room for the beads, and generally improving the routing here or there.