I think those are mostly well justified and substantially add to ergonomics. Await and the reactive operations are used very heavily in many codebases, and especially the reactive code is quite verbose with useState et al. .new allows constructor chaining. Python has // too, and it makes many indexing operations a lot easier to read.

One missed opportunity here is using the bitwise operators for more common use cases. They are very rarely used in this high level languages, and are a bit weird C remnant in them.