Hardly an expert, but it seems more likely to me that GR is the smoothed-out limit of a lot of much smaller stuff happening, than QM is somehow low-level wrinkles in an otherwise perfectly smooth spacetime.

I don't think a smooth anything is physically tractable. You need infinite resolution for perfect smoothness - essentially an infinite amount of information at every point.

Except there are no points. So somehow you have equations that define curvature floating in some kind of metaphysical space which somehow gets mapped to observable phenomena.

And if it's a noisy smoothness - where does the noise come from?