TypeScript 3.6 is now out! 
Read up on better generator checking, better UX around Promises, editing improvements, a new TypeScript playground, and more!https://devblogs.microsoft.com/typescript/announcing-typescript-3-6/ …
Great work 
"--downlevelIteration being off by default works well since, by-and-large, most users targeting ES5 only plan to use iterative constructs with arrays". That's really surprising, I assume you've gathered data on this?