Issue: non-English character is not showing correctly

Sorry, but can you also post a screen of how it's showing?

see attachment, three black triangle.
VB's default language is English. I tried different browsers.
browser's endode setting is auto-detect.

If you are seeing black triangles as in the picture, and the settings are consistent with the previous pictures, then the characters are not included in the UTF-8 character set. There is nothing wrong with the title, and the article is resolving to the correct URL, so VaultWiki is working correctly. The characters you're trying to use in the content might only be available in UTF-16 or UTF-32 and vBulletin doesn't support either of these character sets.

Admincp/language phrase, I set HTML charset to utf-8.
But it seems vbulletin is not fully support utf-8.
I am using vb4.15

So probably setting charset to utf is incorrect.