The reply tool is not able to post replies on page with templated section titles (Buttons and input boxes can be generated, but cannot be published), like zh:Wikipedia:管理员布告板/其他不当行为, is this normal behavior?
Topic on Talk:Talk pages project/Replying/Flow
Thanks for the report. This looks like a bug.
Section titles generated by a template should work fine. In this case, it looks like the problem is triggered by the language variant markup used inside of the template, and how it affects the section ID. MediaWiki's old parser (used when displaying pages) generates different ID than the new parser (Parsoid; used when saving replies), and because of that the tool doesn't know where to put the reply.
For example, this section: https://zh.wikipedia.org/wiki/Wikipedia:管理员布告板/其他不当行为#UjuiUjuMandan（討論_·_貢獻_·_封禁日誌_·_全域-{zh-hans:账号信息;zh-hant:帳號資訊}-）
…has a different ID in the new parser's output: https://zh.wikipedia.org/api/rest_v1/page/html/Wikipedia%3A管理员布告板%2F其他不当行为#UjuiUjuMandan（討論_·_貢獻_·_封禁日誌_·_全域）
I'm afraid this may be quite difficult to fix in the reply tool.
However, maybe you can avoid the issue by making some small changes to the {{vandal}} template or the page. I'm not an expert in language variant support, but I think you might be able to move the language variant markup outside of the template, to a global or per-page definition somewhere? That might fix the problem.
Thank you for your assistance in identifying the problem, and your suggested method has been submitted to the community for discussion, and I hope the Parsoid team can fix this problem.