Why doesn't Digital Editions support international characters?

Well into the second decade of the 21st century, Digital Editions still doesn't support accented &/or international alphabet characters/glyphs at the file naming level. Why?

I have a few not-in-English books where the titles include a few á, é, í, ó, ú, ü characters. For each I get a couple of ??s inside a black diamond shape in the library list. Is there a reason for this in a connected world?

Most operating systems support an extended character set. Is this a legacy code issue?

Anyone there who could address this?

Thanks.