Hello fellow Taiwan lurker! I saw your post and decided it was time for me to add something to the discussion.
I'm not sure about the time last year being March 18th--it looks to me on the spreadsheet that it was around April 18th last year. One thing that gives me hope is it looks like a lot of the countries in the East Asia region got back to the students on a similar timescale (as in within a couple of days of each other). I'm hoping since some of the Korea ETA folks are hearing right now, this may bode well for us hearing in the next couple days.
Regardless, I have gotten through to Jonathan--I wanted to check and see what I could find out so I could tell my PI when I was going to know if I'd be leaving the country in the summer. Jon emailed back (this morning) saying that there was no way of knowing when the Taiwan letters would go out but offered me that they typically go out around mid-April.
I hope this helps, good luck staying in a low stress conformation and I hope I see you in Taiwan!