What you seem to be saying is that gravity creates gravity, and in classical/GR physics that is no problem because energy is poorly defined, so it doesn’t matter if energy appears to be created.
Yes that is a fair summation
In QM, energy is well defined, so it cannot be created. This leaves a problem explaining how gravity creates gravity.
We went thru that under QFT it will be spin 2 boson and will self interact as well as a number of predictable properties but there are things not predictable which needs more theory. So we know why and how it creates more gravity, what we don't know is what stops runaway collapse. No theory of quantum gravity at the moment can predict or produce stability.
1. If we live in a quantum universe, how can gravitational energy be created?
The particles of the other forces in an area of space cause curvature of spacetime and create the presence of gravitons. If the gravitons appeared without the energy/momentum presence there would be nothing to stop a pile of them appearing in an empty space and the universe instantly collapsing.
In a really basic laymans terms it sort of like the other forces coax or squeeze the gravitons into existence which we can then measure.
2. We don’t have a quantum theory of gravity, so how do we know how QM would influence the creation of gravitational energy?
Ask the problem in reverse how is the gravitation force going to work of deal with a mass particle held in entanglement in two places at once.
Is the gravity at one or other position or split between the two different physical locations? How does it do this if it isn't quantum in nature itself?
You probably get why there is a lot of interest in that problem and experiments around it.
