I don't think we will ever be able to go back to older versions than R8, as the CINEMA 4D API completely changed with that version. That means, a port to a pre-R8 will require a large rewrite and I don't have the time for that. I'm already way behind my schedule... But if someone wants to try to port it version, he/she should feel free to do it, that's one of the reasons, why the code is open source.
Beside that, I will look into ports to older C4D releases than 10.5 when the main and urgently needed features are implemented. The build framework is already set up for this. But as I said before, I don't see a port to version older than R8 and very likely I will go back only to R9.x.
PS: This weekend there will be definitely a new release, that allows you to specify Lux render/output settings in the scene. There has finally now been some real progress, as I was fiddling around with description for a while. After that release I will start adding light support. Again, sorry for the delay.