OK, so you don't "tunnel writes through" EventReduce, you "tee" them to EventReduce.
Anyway, to maintain consistency, you have to limit yourself to one process of your app. No sharding, load-balancing etc. This is significant limitation, and it's not obvious. I encourage you to mention it in README.md.
I encourage you to read the readme and check out the demo.
EventReduce is nothing magically drills out your database and affects the consistency of your write-accesses.
It is a simple algorithm that is implemented as a function with two inputs and one output.
And yes, you should always do testings before you use open source stuff. There is no warranty use it on your own risk.