The benefit of looking at languages/scripts in isolation is that the combinatorial explosion of all languages/scripts at once is dodged.

E.g. lookalike charaters, and social engineering by using a vs а. (One is Cyrillic). I don't want to even define "a == а". I want Latin and Cyrillic to be different types of characters, and that expression to be ill-typed.

This solves the Turkish problem, where the upper case I is two different charters in two different types (Turkish Roman script?), and the case folding functions likewise have disjoint types.