I don't think the rules in Unicode are simple for anyone. I have seen professional developers who are native speakers of RTL languages screw it up. All this stuff about the directionality of a paragraph and the embedded markers... It boggles the mind. But a truly international product should be getting it right. Sad mismatch there.

PS: bit of trivia that people forget these days, Win32 has been supporting it for longer than android/iOS.