Obviously, there is no objective wrong/right here, as only the future can tell. My subjective experience tells me, it will be that way.

There is no need to context-switch. Just accept Javascript as part of TypeScript, because it really is. The argument is clear: TypeScript drastically reduces the amount of errors you will be making when coding, and the amount of time you need to think about stuff that is really trivial.

The rule of thumb on how to do this is also simple: Keep your types simple, use them to make your life easier, not more complicated. If you cannot model something simply using types, don't try to do so, just use the dynamic typing escape hatch that Javascript provides.