Cannot display Simplified Chinese subtitles correctly

Here is my VLC settings regarding the subtitles:

• Font: Heiti SC
• File encoding: UTF-8
• Version of iOS VLC: 3.3.4 (426), based on 3.0.17.3-207-ga7254c78ea

The source subtitles is a UTF-8 file, and within range of Simplified Chinese, but some character will just blank out. E.g. 杂 as shown below.

I tried:

• Switching to Traditional (Big5) and Heiti TC, result: character becomes an X Tofu
• Changing to other fonts which are not Chinese, result: Blank characters

Possible solution:

• Some .ass subtitles specified the fonts, which is not Heiti SC or Heiti TC, and iOS doesn’t have those fonts, but they displayed characters correctly anyway; fallback to system font is a possible way
• Include fonts like Noto Sans CJK to the player. This will solve it without further explanation.
• Allow user to add custom fonts via iTunes Files sharing. Note that only users with legally obtained font files on hand can use this feature, so the legality depends on users.

This is played on VLC iOS:

And here is a reference of correctly displayed subtitle