How does Unity handles internationalization ?

Internationalization is a big thing in gaming, but I was surprise to see this

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when searching on unity website.
How are we supposed to handle hundreds of translated strings ? Only way I could find on google is to make a class and a dictionary to keep all the text. This is very (not) efficient and wasted memory.

Is any way to read from binary files like ".mo" files ? Or a more optimized solution except reading hundreds of texts in memory...
Thanks