I, too, have the Ł letter in my name, and yes, it is a sick joke that so many things even in a supposedly modern systems make an assumption that the world runs on ASCII.

In the case of the Windows operating system, the worst fact is that every single part of it behaves differently. Some parts display the path with a wrong encoding, but handle it correctly. A third-party app can display it correctly, but fails while trying to access any file. From what I remember, even the built-in PATH variable editor/manager goes through some arcane steps to display the letters in a wrong way, but getting them to work sometimes.

I can only imagine how much more pain it is for someone using any of the less widely-used writing systems or those with more advanced features compared to ASCII (Hebrew’s RTL, Arabic scripts mid- and final forms, etcetera).