1) Why are we talking about space curvature as if we know what space is?
Every question about gravity seems to evoke an answer involving "space curvature" which seems like an undefined placeholder concept no different than 'ether'.
2) Can we define what "space" is and how its elements (and which of its elements) curve before we use it to build other definitions?
3) Are we truly confident that gravity propagates at the speed of light?
4) and is that truly the limit of gravity itself or is it the limit of the methods of its observation (themselves involving light and devices based on electromagnetism)?
5) Or is it the introduction of the undefined concept of a precurved "space time" our indirect acknowledgement of instantaneous propagation?
The use of math can be a conceptual trap since the practice tends to provide accurate extensions cantilevering from original presumptions. Much like with Zeno's paradox, math does not negate the presumption, but merely confirms Achelies' distance to be asymptotic to a limit (the limit artificially set by our original presumption).
6) How confident are we really today that the speed of gravity is a done deal?