So CTBC just called me back to say the following:
(1) It had taken them a while to get back to me because they’d had multiple complaints about this (@Mataiou I guess, but I got the impression it might be more) and they were dealing with them together.
(2) The 183-day and 10% vs. 20% withholding thing is probably just how it’s going to be, because they have no way to know how long we’ve been in Taiwan for a given year. Unless we want to go into a branch with proof of our time in Taiwan each year.
(3) She needed to ask her supervisor to check about the CRS rules for foreigners but agreed “GB” or other country codes probably shouldn’t be listed on the forms for foreigners wholly tax resident in Taiwan (not including U.S. citizens), and that I should expect an e-mail from her supervisor “in a few days”. I mentioned I’d complained to the FSC and MOF as well.