That's why the search functions need to be more intelegent. If you pass the search function a grapheme it will do more work. If it notices you just passed in a grapheme that's just a code point it can do a code point scan. And if the internal representstion is UTF-8 and it sees you passed in an ASCII charzcter (very common in lexing/parsing) it will just do a fast byte scan for it.
Now if the spec thinks identifiers are just a collection of code points then it's being imprecise. But things would still work if the lexer/parser you wrote returns identifiers as a bunch of graphemes because ultimately they're just a bunch of code points strung together.
It's only in situations where you need to truncate identifiers to a certain length that graphemes become important. Also normalizing them when matching identifiers would also probably be a good idea.
