IMO if you are using React, you absolutely should be using Typescript for UI on non-legacy codebases. There is most certainly a learning curve in understanding why Typescript seems to show you errors in your UI code, but once you understand the ~5 most common errors it becomes much, much easier to use Typescript instead of JS. I simply won’t use React components (or other libraries for that matter) from NPM if they don’t have Typescript typings (or if I can’t easily create an abstracted shim over the untyped code).

The benefits to using Typescript are immense.