Thanks Tando for finding another official statement on this topic.
This 2021 letter, 勞動發管字第11005117021號函, starts out by recapping what we already know from earlier in this thread and then briefly looks at eight scenarios involving a fictional Indonesian called 小明. (Go to the PDF link at the bottom of the page to read the scenarios.) It keeps referring back to the 2018 letter and making the point that whether or not an activity is acceptable without a work permit depends on the details. For example, scenario #8 asks whether or not 小明 can be paid for appearing on screen or on stage. The response:
移工小明受邀擔任電影或電視或戲劇等角色，尚須視拍攝內容及擔任角色等，若其符合 107 年 11 月 27 日函釋附表五（七）要件，參與移工議題紀錄片拍攝及角色，則非屬本法第 43 條規範之範疇。
To paraphrase, it’s acceptable if it conforms with the criteria of category #5, subcategory #7 in the 2018 letter, which gave the example of appearing in a documentary about foreign workers and pointed out that it doesn’t affect the local labor market, even if there’s some form of payment.