Thanks for this – I really appreciate the insight. That changing-input lag sounds like an absolute nightmare.
Since I left my previous comment, I came across some Apple presentations on new work they've been doing in iOS 9 and iOS 10 on internationalisation including RTL and mixed-content support. It sounds like there's a lot of work still to do, but I was pleased to see they've at least started multilingual input sources now (in iOS 10, autocorrect can work with multiple languages without having to switch keyboards, though I'm guessing this only works with Latin alphabet languages for now?).
Since I left my previous comment, I came across some Apple presentations on new work they've been doing in iOS 9 and iOS 10 on internationalisation including RTL and mixed-content support. It sounds like there's a lot of work still to do, but I was pleased to see they've at least started multilingual input sources now (in iOS 10, autocorrect can work with multiple languages without having to switch keyboards, though I'm guessing this only works with Latin alphabet languages for now?).