As someone who've learned Q3D via trial-and-error and some frustrated educated guesses, I've had no actual major problems understanding nor relying on Q3D to do it's job.
Obviously documentation is a big plus (and something I also would've liked in the beginning) with plugins like these, but it is in no way mandatory. Quazi has created something that wasn't supposed to be supported by Construct 2 in the first place - alongside plenty of update information every time he adds onto it, and taking his time to support Q3D users with their questions in this thread. I've read through some pretty nasty and naive comments here, and Quazi always seems to be able to answer in a professional and patient manner no one should take him for granted to have. I believe we're forgetting that he's just one person (talented one at that) whom at some point decided to make an excellent plugin and then went out of his way to keep it stable and feature-packed by the best of his abilities, and I commend him for every second he spent doing that.
His brother recently released a game that I've been looking forward to (Towerclimb) - and even then, Quazi has every right to be busy whenever he likes to be. This is not a commercial product backed by tens of people, it's one hobbyist pulling the strings and asking for the equivalent of three substantial dinners in return. No pay-per-month bullshit, no pay-per-update shenanigans - he's as humble and as reliable as can be in my eyes. And with that, In my opinion, you should be satisfied with what you bought since the only problem here is documentation, something he has since proven is on it's way.
He could've just released the first version and leave it at that, but he does try to keep it an understandable, working, semi-regularly updated plugin for something that otherwise would require a java programmer to achieve. Going the other more painstaking way around, Playmaker for Unity costs $65 as of writing - and should give you enough to emulate Construct 2's event system in a fully-fledged â‚¬ommercialized 3D-engine alongside probably plenty of documentation.
So please, respect Quazi's private life and his personal will. When he wants and has the time to work on the plugin, he will do that.
I got here to ask about how to render a Q3DSprite's magnification filtering by nearest instead of linear, but was pleased to see the plugin is still in progress and hoping it'll be in v2.5. Until then - I will work with what I have, refer to this thread for common answers and just ask questions when I'm full-on 100% stuck. For more beginner documentation than what Quazi just linked, you may also want to check out http://3dswing.com/ or CTRL-F on the first post to scan through update information with keywords. Otherwise, some of the most confusing little problems for me has had the most simplest of answers in places you don't even think about looking in. If you're curious how to achieve something specific, you can also look at the demos referenced on the website I linked or on the first post, otherwise you can always try it yourself and learn from experimenting.