You are the only one talking about time flowing. At least in the context it seems you use. There is no direct connection between optical clock rates and the speed of light. Whether space is or is not homogeneous or inhomogeneous, requires first a far better description/definition of exactly what you mean by the word space. I think, in context Einstein was referring to spacetime, rather than just space. Again with the reference to Einstein's Leyden address, which you have repeatedly shown you did not understand. Remember CONTEXT, CONTEXT CONTEXT. That was an address intended for a specific audience, whose background was rooted in the aether theory, preceding century. The ideas Einstein was presenting had not yet made their way into basic undergraduate education. In short, had he known he would be talking to you, he may have kept his mouth shut!