I think that you are using the word “aliases” differently than me and others, such as the Obsidian team, and that’s fine, but can you identify the problem that your concept aims to solve? You are thinking in terms of translating page content (blocks), but the core issue aliases are meant to solve is translation among links to the same content, not links between pages with differing but related content.
Aliases are (or should be, I think) different terms that refer to the same content (for Obsidian, the same file, for Logseq, the same page). A translation is not the same as the original. It is different content. Aliases are not the right way to solve the problem of linking related but different content in different languages. Aliases are the right way to solve the problem of linking to the same content using different names.
Thus, it does not make sense to me to say that aliases can “have their own contents”. If you have two pages with different content, e.g. one in English and one in Chinese, then those are different pages. They should not automatically redirect to each other and links to one should not automatically link to the other. If two pages have different content, then there is no “source page”. Each page is its own source.
You say that “mouse” and “mice” are equal in their names but not always in their contents. Stepping back from the current way you are thinking about the issue, does it really make sense to have 2 pages with different content but names that are considered equal? What is the problem that such a system is aiming to solve?
Different content should have different page names, full stop. There already many ways to link pages with different content, even if it is similar or just a translation. Link the English page and the Chinese page with regular links, create a page that embeds the two source pages, or run a query. But there is no other no other convenient way I know to link to the same content with different names other than aliases as I described them.
I’ll respond to the other questions once we get this issue more settled.