Yes we still don't know exactly the speed of gravity and as it stands we know it to be the around the same speed of light with a margin of 70% ( https://arxiv.o

Yes we still don't know exactly the speed of gravity and as it stands we know it to be the around the same speed of light with a margin of 70% ( https://arxiv.org/abs/1602.04188 https://arxiv.org/abs/1602.04188 ). But with so many theories at play, we still don't know for sure. Indeed, some still believe that the speed of light has changed over time - hence https://en.wikipedia.org/wiki/Variable_speed_of_light https://en.wikipedia.org/wiki/Variable_speed_of_light . Which as a theory, if true, would really mess up distant astronomy calculations for some. As you say, would be nice to have some definitive experiment that reduced the margin for error and give a more definitive speed for gravity. Though current results do tend to lean towards Einstein being right more than Newton in respect to the speed of gravity.