The export data text become encoded unicode after reimport
I have exported the whole website for a backup and re-import again to wordpress. I found that the exported attachment data like with 3 images for that post:
Originally, the text written to database is "M21媒體空間海報" by checking up to database field soon after update the post, after export, the text become JSON_UNESCAPED_UNICODE "M21\u5a92\u9ad4\u7a7a\u9593\u6d77\u5831"
However, when the data is being import again. it does not restore to "M21媒體空間海報" but keeping "M21\u5a92\u9ad4\u7a7a\u9593\u6d77\u5831" instead.
Although I think it due to the export and import mechanism of Wordpress, it might be good to post here for consultation for someone having the same problem and discussing for solution.

Hi there, it could be due to WordPress' export, yes. I plan on reworking the storage of Attachments from the ground up to better accommodate unicode errors but that won't be until the next dot release.