Phusheeto52 If I buy a ticket for the 12:09 PM train can I take a later train if my flight is late?
Normal tickets are for a route, not a train, so you do not, technically speaking, buy a ticket for the 12:09 train.
(note: railways use the 24 hour clock here, better get used to this :-).
So you buy a normal ticket Zurich - Airport to St. Anton, and you can just take whatever train on that day on that route.
You can buy a discounted ticket that has “train binding”, where you commit to taking a particular train in exchange for a discount, but that would not be a good idea in this case.