I forgot to report back. I have a new passport issued June 2018. I updated via the DHS portal, and this reflected on the NIA side shortly. I brought my old passport just in case, but I had zero issues using the new passport entering Taiwan in December at T2. I aligned the left edge of the passport with the light as before, and it worked on the first try.

As another data point, I also had no problem with Australia's SmartGate in November, so I haven't experienced the same issue reading a US passport that others have.