Next step: Vertically center the ellipsis in the manner of other East Asian typefaces like MS Gothic.
There isn't actually a glyph for '…' in SimSun-ExtB; it's shown in your default font.

This is a monospace serif font, which is why I like it. I don't want to spend every day programming in Consolas, lmao.

Ending with Windows XP, Chinese versions of Windows were shipped with a default font of a member of either this font's family or the "Ming Liu" family. Past that, Windows never defaulted to serif.