When I import, there is no release artist set.
The release artist is indeed not shown on min tracklist popup, but it is on parent (?) window in the アーティスト column.
Best: Can you get data from this main page?
Or if not, but it would be less optimum, can you set release artist when 100% track artists are same like here?
I am testing your great import script on a desktop now (Raspberry Pi Debian 10 and Chromium 92.0.4515.98).
https://search.minc.or.jp/product/list?dn=FLCF-3850&type=search-form-diskno
When I import, there is no release artist set. The release artist is indeed not shown on min tracklist popup, but it is on parent (?) window in the アーティスト column.
Best: Can you get data from this main page?
Or if not, but it would be less optimum, can you set release artist when 100% track artists are same like here?
Just my quick ideas...