Your argument is that TS blindly trusts 3rd party typings, but Kotlin has the same exact issue! In fact the Kotlin docs say to use TypeScript typings, or "dynamic" (read: unsafe) mode for 3rd party libs. So I would expect the same level of safety between TS and Kotlin when it comes to 3rd party libs.

I personally prefer TS because it's safer: with literal types and mapped types, my code is far safer than the equivalent Kotlin. It will surprise you how often you use these features.