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It does remind me of the Real World repository [0]. It is basically a Medium clone implemented in tons of different frontend and backend frameworks. Probably not exactly what you were looking for, since it's more related to the frameworks rather than the programming languages, but it is still interesting nonetheless.

[0] https://github.com/gothinkster/realworld

The Lox Language is another teaching tool by Bob Nystrom with many implementations [1] and a great (work in progress) book [2]

[1] https://github.com/munificent/craftinginterpreters/wiki/Lox-...

[2] http://craftinginterpreters.com/

Not exactly what you're looking for, but: https://github.com/mame/quine-relay