[sirn]

> the characters that got unified do share the same semantic meaning across languages

It doesn't in practice. For example: 机 in Japanese means "table", while the same codepoint in Simplified Chinese means "machine" (i.e. 機 in Japanese).

[vore]

For that example, in Chinese 机 is an alternative orthography of 几 (https://en.wiktionary.org/wiki/%E6%9C%BA#Etymology_2) as in e.g. 茶几 – it's not perfect, but language is messy and I don't think Unicode did the worst job of a messy situation.