I’d consider that “salary and wages”. Not a tax advisor.
(IMO, there’s some amount of discretion here because of how poorly defined freelance work, especially overseas freelance work, is in Taiwan. I suspect if you filed it as salary/wages it would be fine, and if you filed it as professional practice income (and paid more taxes) it’d also be fine and nobody at the tax office would try to convince you otherwise.)
I’m not really sure about all the requirements here. Some reading material for you:
Can’t attach PDFs here, so I sent you a PM with the official list of documentation required for overseas income, dependents, etc.
