From what that page describes, it appears Twitter's algorithm is in fact "number of unicode code points" except for specific carve-out cases which are so obscenely unfair by that metric as to justify counting differently. E.g. counting Unihan characters as two makes the 280 character limit in these languages be approximately the same limit on information as western languages, since they are about twice as compact in terms of information density. And emojis are an insane amount of unicode code points, particularly when modifiers are applied. Etc.