Thanks for posting... I was looking for something just like this:
Feel free to use CoffeeScript to implement your libraries, but lets just call it a JavaScript library and assume everyone who uses CoffeeScript will understand they can use any JavaScript library.
When having to choose between a library written in JavaScript and a library written in CoffeeScript I choose the latter, because it statistically has a probability to be a better library, just because the coder didn't have a chance to use bad JavaScript practices, when writing it. Assuming I usually don't have time to read the code of the libraries I'm using.