Another reason why nobody saw these 200,000 troops might have somthing to do with the fact that nobody was looking on that side of the border. A chinese attack on Taiwan is'nt going to come from Japan, as soon as tensions flare up, you can bet on dozens of inteligence assets looking for Chinese movements.
An airborne invasion requires at least partial air superiority, especialy if your going to move large amounts of troops. Airborne forces are traditionaly light infantry, good at moving, bad at holding, especialy for long periods of time. (exceptions being 101st in the Ardeness). Remeber they are taking on the entire Taiwanese army on home soil, not including tameing the civilians aswell.
This brings you back to sealift, which cant be done quitley or easily.So the question is, can they adequatley protect these sealift assets?