Spectral is spectral. We can’t get “closer” to it via RGB. I’d need the direct quote to bring it up in any sane manner though. Link?
The “closest” we can get to spectral within an RGB encoding model is using spectral -like primaries, such as BT.2020. Within that, because the nature of the RGB model is based on top of the CIE XYZ model, it all falls to 
, and can’t ever get close.
So until all rendering subsystems migrate to fully spectral rendering, we are out of luck. On the upside, it seems that more than a few engines are migrating that way.