Washington announces it now has the capacity for low speed passenger trains to get stuck behind grain freight and go even slower so it takes take 29h to get to Chicago.
Mainland China is about 100 miles away. Thats a damn long distance. Strictly from an engineering perspective, that would be incredibly impressive feat if they did it.
Did a quick search and it looks like the longest rail bridges now hit a max of roughly 1/4 what this Taiwan-to-China bridge would need to be.
True. But this would not be a cheap project if they legitimately attempted it, so they probably would want to keep the Chinesium quality to a minimum so it doesn't fall apart after it's first use.