master branch of nodebb-grunt-development however isn't doing best to use CoffeeScript with Node.js (since I wrote it when I was absolutely new to node.js), it's concatenating coffee-files and compiling afterwards. Thus not allowing to use node.js require-structure within one module.
rework branch however attempts to improve this (and abstract of just CoffeeScript support in advantage of providing features for any kind of development tools). It's not finished yet since I've been busy with other sort of things lately (6 months o_O I have to get back to it some time soon I guess xD ).
So for now it might be the best for you to create your own grunt-tasks in order to compile CoffeeScript (at least if you need multiple internal files connected with node.js require).