The thing about Coffeescript is that you don't really gain anything other than syntactic sugar. Compare it to, say, Typescript and Clojurescript where you gain a whole set of features and, with Clojurescript, the semblance of a standard library.
I really don't remember it was a long time ago but from what I recall there was just too much magic happening and things would break a lot of times because it was easy to make mistakes with it.
Come to think of maybe I didn't learn it well enough at that time and blamed it for my silly mistakes. CS did introduce a lot of good things like the fat arrow which was just amazing at that time.