To replace files quickly and correctly, follow these steps:

1. Go to Steam > Scrap Mechanic > Properties > Local Files > View Local Files

2. Let's go to the /Data/Gui folder and transfer the Fonts2 and Layouts folders there

3. We return to the Scrap Mechanic folder and follow the path /Survival/Gui/language and throw the Russian folder here

4. That's it, you can enter the game, set the Russian language in the settings and play!

Video instructions - imgur

Error in translation? write to telegram - @shandeika0

The translation is somewhere around 75%. Sorry, I only managed this in one night.