This may be of some help to you:
There is a thread on here about it, detailing. progress and some of the snags I encountered along the way:
It’s a Music & Midi node system, written with its own node editor and complete structure with menus, resources, etc. It may be more complicated than you need, but it will show you how to build such a system. It is still WIP, so there is little code documentation, docstrings, etc and definitely no help files yet… Anyway, it might be helpful and I am happy to answer any questions you might have.
It is the first node system I have built so might not be perfect, but it all works. One thing it does show is how to pass multiple variables through node trees. I use dictionaries for this and pass them through only one output socket per node. I found this to be the easiest and more reliable method. I have also done quite a lot of development with AN, you can find that on my GitHub too, but in the end AN became too big for what I wanted, so I set about writing my own node editor. You will see that I can run this either one frame change, or via a timer, that bit might also help you get your tree to execute.
If this is useful and you have questions, just fire away!
Cheers, Clock. 