I'm not actually familiar with blender or how that works with AE. I didn't work much on creation of the different compositions, just the end product, so I'm not sure what technologies our designers and animators may have worked with.
Presumably, if blender formats the composition in the supported structure and doesn't drift outside what the library recognizes and supports, it should work.
Hey, zigzigzag! The reason we went with JSON initially was for ease to work with, debug, and general ability to tweak and make the development process for this project much easier. That's definitely not to say there aren't some notable improvements we can make to this library!
I'm one of the developers at Facebook who worked on this library since its conception! Really excited to be able to share this library today! I'll be checking up here periodically and can help answer any technical questions that you have!