Actual terminal-based TUIs sure, they have small character sets burned into ROM, sized for 50-years-ago prices.
Modern terminals, even the text-based console on a fresh minimal Arch linux install, is going to support Unicode probably without a ton of issues as long as you have a font installed that has the characters. The struggle then for RTL or non-Latin character sets and languages is making the UI fit the words in a way that makes sense.
Yes, you can spend an inordinate amount of time figuring out how to lay out multilingual text on a terminal, or just use Cairo or some toolkit and let solved problems stay solved.
Modern terminals, even the text-based console on a fresh minimal Arch linux install, is going to support Unicode probably without a ton of issues as long as you have a font installed that has the characters. The struggle then for RTL or non-Latin character sets and languages is making the UI fit the words in a way that makes sense.