Thought about using a stricter style guide?
In my opinion, AirBnB's style guide is the best of them all. It could also help you move over to ES6 eventually since they're working on that, too.
Also, lose the damned tabs!
Hmm, idk, some parts of the code could use better adherence to a style for consistency, and it may encourage new contributors.
I feel like styles are largely based on opinion though. And in situations where a style does help, such as avoiding confusing/ambiguous expressions, NodeBB rarely suffers from these problems.
I am against tabs though. I hate them. Used to love them, but after using spaces, i can never go back. (I really really hate semicolons too.)