Update, but not a great outcome.
I did as what TECO SF suggested, took my mom to TECO SF and had her sign power of attorney for a friend in Taipei to lookup her household registration office. TECO wouldn’t allow her to sign the power of attorney using her Chinese name, only her American name. At the Taipei household registration office, they confirmed they found household records for her but wont’ release them because they’re not signed by her Chinese name.
I had done a FOIA for my mom’s American and the USCIS provided her original US Visa application which features her Chinese name. TECO did not accept this as any proof of her Chinese name.
Any ideas on how to provide her American name and Chinese name are the same person?