Case-insensitive ext4

I am Dutch, currently living in Germany, and often conversing in English too (like here; plus sometimes receiving Czech documents). Now, none of those are really difficult cases, I think (SS/ss and ß notwithstanding), but they do have differences in how characters need to be interpreted, but while my usage is for a large part context/file dependant, there are overlaps in what I use when, sometimes in a single context, like in chats, online, and sometimes stored in a single directory, due to where, by whom, and for what a document was created.

Not sure how what you propose can work correctly when generalized. Imagine I for some reason add Turkish in the mix too, or when I use a more complex, different set of languages as daily use.