Honestly? Convince operating systems to have a switch that enforces UTF-8 path names, and then convince distros to flip that switch by default for new installs. That is to say, we need to move the world from a probably to a definitely state.

The reality is that file names are "stringy" in nature--people expect to be able to do display them--and that means you need to have some up-front agreement on how to interpret those strings. In practice, on Unix systems, everyone has generally agreed that this is UTF-8, to the point that trying to not be UTF-8 generally causes interesting breaks in the system. It would be great if we could actually get the operating system to help enforce these rules, rather than placing the blame on other software for not correctly handling situations where the correct solution is itself incredibly ambiguous.