> that not everybody writes in English.

I don't know... I understand the history and reasons for this capitalization behavior in Turkish, and my native language isn't English, which had to use a lot of strange encodings before the introduction of UTF-8.

But messing around with the capitalization of ASCII <= codepoint(127) is a risky business, in my opinion. These codepoints are explicitly named:

"LATIN CAPITAL LETTER I" "LATIN SMALL LETTER I"

and requiring them to not match exactly during capitalization/diminuitization sounds very risky.