But as for the second question: for HTML documents, many tags have a lang attribute that decide which version of the glyph to render within that tag. Hacker News has lang="en", so it'll use a user setting to decide. For example, in Firefox' about:config, there's a setting called cjk_pref_fallback_order. If e.g. ja comes first, the little square inside the top square in 骨 is rendered on the right side, if any zh thing comes first, it's rendered on the left side.

For instance traditional chinese in china will be left 過. Most computer systems will type this one

But in Taiwan they do right side (you cant even copy\paste it though)

And simplified is entirely different 过

https://en.wikipedia.org/wiki/Han_unification

My understanding is that this is basically "white guy says all Asian writing looks the same" in standards form and is largely regarded as a terrible idea.