Unfortunately, it
is an issue if you're not a regular CoffeeScript user yourself. If you're making significant use of any framework, at some point you're going to have to dive into the internals and figure out how it works or why is isn't working the way you expected.
With a CoffeeScript project, you either have the choice of reading code which wasn't generated with humans as its target audience, or code which actually expresses the author's intent, but using a language you don't normally read or write, which comes with its own bunch of constructs and idioms which you need to be able to transpile on the fly in your head to understand.
In that case, gods help you if the author has gone overboard on CoffeeScript's Rubyisms or used @ in a particularly esoteric way.