[RedNifre]

It depends on the language and/or used libraries. E.g. in Go, the problem does not exist, because it uses UTF-32; Rust uses UTF-8, but it makes sure that you can't cut a string between bytes that belong to the same character.

Fun Java/macos quirk: macos normalizes file names, so you can't have two files called ü in the same directory by writing ü as a single character and as composing characters. But unfortunately, this only happens on write, not on read, so if you type an ü on a German keyboard (produces a single character) into the Java source code file when writing a file name, the file will be saved with the decomposed name instead, but when trying to open the file, it will not be found when trying to open it with the single character name.