@qwert_zuiop, my experience doesn’t match what you were told. I just flew a couple of days ago from SFO to TPE on EVA Air.
I did not have a test result. The lady at the check-in counter at SFO asked me whether I had a test result. I replied that I had an ARC and gave her a print-out of my 境外核准證明 (Resident Authorization certificate). She said that she needed to check with her supervisor. That only took a few seconds, as her supervisor was standing a few counters away. No one asked me about a residential address in Taiwan, and my print-out does not have one because I did not indicate one in my Gold Card application.
On the 境外核准證明, there is a box labeled “在臺居留地址(或飯店名稱) Residence Address in Taiwan(or Hotel Name).” The fact that it says “hotel name” suggests that if necessary, you could just put the address where you will do your quarantine. But again, I don’t think it’s necessary; as I mentioned, on my form this field was blank, and I did not have any issues flying here from the States.