The traditional Mongolian script is notable for being written vertically, which breaks a lot of assumptions usually made in UI design. The Mongolian president's personal website is an example of designing around vertical text: https://president.mn/mng/
The closest I've worked with is a booking website for an international parcel delivery company. We offered the application in idk, dozens? of languages. Hebrew was one of them, it's a right-to-left language and our whole website became right-to-left when switching to that, so the main menu was on the right instead of the left, things like that. Great work by our CSS people.