This is not new news any more but I did not see this mentioned anywhere on FT. 12306 now has an English version and accepts international credit cards (VISA, MASTERCARD, JCB and Diners). You can also register with an email (no Chinese phone number required). I have not tried this myself yet to see how well it works.
You can book paper tickets, etickets and change bookings.
https://www.12306.cn/en/index.html

Great. Thanks for the heads up. I'll try it next time. trip.com will lose its booking fees if it works.

That's amazing if it works with US credit cards. I'm anxiously waiting for data points from any American in China at the moment.

I'm British not American, but I can confirm that it does indeed work with a UK-based MasterCard. Only downsides I've found so far are that I can't select seats, so my group of 2 is split across 2 rows, and the payment currency is RMB, so I'll get hit with an FX fee from that MasterCard.

I guess the real test will be when I turn up at the station in a couple of weeks for my journey, but so far, so good.

Good news that your card work. Sucks that there’s no seat selection. Hopefully, that problem will be rectified in the future.

There is no seat selection on the Chinese site either. This is how it works. But the system allocates seats next to each other except when it is not possible because most of the train is sold.

So the only way to guarantee a window seat is to book in person?

You book. If not window, you cancel and book again. Repeat until you get a window seat (assuming that some are available).
If you buy at the station on travel day, it is very unlikely that you'd get a window seat.

You can choose your preferred seat (window/middle/aisle) on the app. You can’t specify which row you’d like to sit in but you can choose window or aisle.

You are correct and this option does not appear to be available on the English website.

Ok yeah, that sounds similar to what Trip.com offers - you can choose the layout for your group in terms of left/right, aisle/window, forward/backward, but not specify row numbers. It seems silly that 2 tickets sold together wouldn't be next to each other, but I'm not paying £6 to Trip.com for the privilege of fixing it unless it's a very long trip!

Two ticket bought at the same time will always be next to each other (unless the train is almost full). Just buy them and if you don't like the seating arrangement, just cancel right away.

The waiting list option mentioned earlier in this thread does work and is available to foreigners.

However, it is only available on the Chinese language version of 12306 (web and app), not the English versions or on trip.com.

It looks like China Rail is heavily using the waiting list to manage tickets, so it's an option to consider when you see "Sold Out" on the English sites.

I booked sameday R/T travel on Trip.com for Shanghai-Yiwu-Shanghai for the first time since paper tickets were
eliminated. I was surprised at how well the entire procedure worked. Passport scans at security, boarding, and exit
went smoothly enough - I just learned that at boarding and exit I have to line up at the manual line rather than the
automated toll booths. I definitely liked the fact that I no longer have to line up an hour in advance at the ticket windows.

It may vary at different stations with different equipment, but I've found passport scans do work at the "ticket" scan entry/exit gates inside the stations but not at the security check gates outside the stations, where you have to go through the manual line.