I am confused about how to add these. Whenever I go to enter a Game Card, it just gives me an option to enter a CD Authentication Key. In US wow, these are different, what about taiwan wow?

TWoW do not use blizzard game card instead they accept locally made points card. read this thread again, it tells you how to top-up your account.

remember this....450 points card = 30 days unlimited gameplay.
if you get any other points card, it allows you to play under hourly point deduction system (1 hour = 5 points)

click here: https://wow-in-chinese.forum2jeux.com/want-to-join-us-want-us-to-join-you-any-request-f5/first-post-anyone-on-tw-realms-t512.htm#6163