> for points that are separating faster than the speed of light due to inflation gravity couldn't alter that space.
This is not correct. The effects of inflation on spacetime geometry are a form of "gravity" as far as GR is concerned. They're just not a form of "gravity" that you could ever get out of the Newtonian approximation.
I don't see how this could work. Say there's a significant increase in mass at a point in space A. And there's another point B that's where the distance A-B is separating faster than the speed of light. How could any changes in mass at point A alter the spacetime/gravity at point B? Are we presuming a means of propagating changes faster than light via graviton?
This is not correct. The effects of inflation on spacetime geometry are a form of "gravity" as far as GR is concerned. They're just not a form of "gravity" that you could ever get out of the Newtonian approximation.