Multi-language support on R flexdashboard

Question

I would like to add language support into my dashboard relied on R flexdashboard. Currently figures, axes, titles, etc have only single language but I would like to extend the entire content for multiple languages. Basically the user should be able to select which language he/she needs throughout the panel. What is the best infrastructure in order to handle this scenario? Language selection should be handled with action button (at least for 2 languages)? Contents should be stored in a json file? Any implementational suggestion or minimal code example for this scenario? Thanks in advance