I was looking into using RQL in a research project called Periscope. It's still in early stages but a public copy of the repo is at https://github.com/periscope-ps/periscope/blob/iu-merge/peri-tornado/.
However I ended up implementing a subset of RQL for two reasons 1) my REST API didn't need all the features in RQL (well, it's nice to have it but I have time constraints!), 2) pyrqlate was not registered on pypi. Though, I hope to switch my current naive implementation with g pyrqlate in the near future.