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That's an interesting question. I've never thought about it or seen that taken into account (its not something we fit to when constraining cosmology)

I just looked around and LIGO has constrained Omega_GW < 1e-7 (they find no evidence, but that is the limit of their sensitivity). This is at least an order of magnitude smaller than Omega_Radiation and so will have a negligible effect on cosmology/total energy content.

https://arxiv.org/pdf/1612.02029.pdf

We have estimates of the energy or mass formed into black holes, and at the end of the day this is just black hole energy that happens to have been later converted into a different form.

Ignoring dark energy, we expect gravitational energy to be identical to non-gravitational energy; ie, “half”.