MCLangSplit

This mod injects a configurable second language into all text strings in the game. This could be useful for learning a second language without having to keep switching between languages. This mod has been designed to be purely client-side.

There is a hotkey for cycling though the configured language modes (default R):
Original -> Alternate -> Both

This mod supports Cloth Config on both Fabric and Forge - as well as Modmenu on Fabric

Check out the Wiki for information on configuring this mod:
https://github.com/AntMCDev/MCLangSplit/wiki/Configuration