The basic concept of gravity travelling at the velocity of light was a result of the field equations,
and not something in addition to it, as the quotes show in the starting post.
Consider this:
If gravity and light travel at the same velocity under the same laws of physics then they must both follow the same trajectory. So if your interpretation of the Relativity laws resulted in it appearing "as if" gravity had the same origin under Relativity as it would under Newton,
then light would also appear to be originating across the midpoint and it would thus be impossible to measure
the velocity of light by observing the moon's of Jupiter.
So if gravity follows a different path to light then it would be wrong to consider them
as having the same velocity, and operating under the same laws.
The logical errors you and almost every other theorist in the history of science and philosophy make
is to think that quoting esoteric jargon is the same as understanding. Its not.
You need to start by programming "triple orbit software" (or "multi-orbit software") on a purely Newtonian level.
You probably would like to scoff at this; thinking it is beneath you,
but I still see no evidence that you or anyone else fully understands how to do this.
n-body Newtonian gravity is certainly simpler than Relativity,
and yet Hawking clearly states:
(Brief History of Time)