You can't make 11100 with 10 and 101, only 10101 or 10110.

Correct me if I'm wrong but I think JS tests are incorrect. For example:

Expected: '10110', instead got: '11100'

But '11100' is a bigger number than '10110'.

The reason your code fails is because you copied descriptions of invalid tests and thought they were meant to be the result, but the instructions say:

It should default to English ... in the event of an invalid input.

So, your foreign environment pass your code because it has been given incorrect results. The correct expected results are in place correctly here on this site, so you must base your code on that.

If you cannot prove that the kata has flawed code, do not post as an issue, post as a question. "It works on my machine" is not enough of a basis.