If you can use Google fonts, try Noto Sans, Noto Serif and Noto Display fonts. They are supposed to work across all languages and alphabets with no need for encoding language-specific characters.
I use them with Polish language and they work fine. To type them into my project, I have to use a workaround, which is not the ideal solution, but it works for me. I open “Emoji & Symbols” (Command+Control+Space Bar). In the window that opens I choose ‘Latin’ set of characters, I select all characters that are specific for the chosen language and add them to ‘Favorites’.
Once this is done, I just double-click a specific character to add it to my text in RW.
BTW, if anybody has a better/faster way of typing in non-standard and foreign-language characters, I am open to suggestions…