I haven't used CS, but I expect its JS output to be more verbose than if someone had written the JS themself. This means the people trying to contribute with CS

I haven't used CS, but I expect its JS output to be more verbose than if someone had written the JS themself. This means the people trying to contribute with CS-JS will be adding longer code that doesn't fit with the coding style of the project, and will be much longer. It may be possible to change CS to output less verbosely, or to ignore the difference. I think the library's main writers will ask for contributions to be in JS, so it can be written to their coding style.