It may be worth exploring doing a service wrapper for Carbone, I think it would make for a nice simple Report API engine. I would make a template (using MS Word or LibreOffice) and upload to files, and then use codeless to create and pass data via JSON to receive PDF etc… out. Your system is iching for a slick (and easy) way to get reports out, this might be an option to get started on that.
If there was a way for me to install LibreOffice on your servers I might try and use Node to expose Carbone as a service in Backendless, however I am trying to keep my current project strictly codeless so instead I will use the Carbone hosted API directly for now. I just thought it would have been awesome to have a Carbone (or Carbone-like) engine powering a Report API directly in Backendless.