This is indeed a bit of a iffy workaround, but maybe it's because Corona fixes the edges of the cube, ie no holes between the sides?
I can't double check with V-Ray since it doesn't have an infinite demo version with watermark, so:
I see that in FStorm it only makes this fix if the smoothing groups of the object are set up that way. Maybe Corona should have a switch somewhere where you could change how you want it to behave? Since it doesn't seem to respect the smoothing groups in the same way
Talking about this specific displacement example, how do people fix the jagged displacement from Corona without maxing out their RAM? It's a headache trying to get clean looking edges(see attached). I have to bring screen size all the way down to 0,2 px, and then it uses like 8GB of RAM and adds 5 seconds before it shows up in the VFB.
Are there any plans to improve the displacement? I'm not sure if you could "steal" something from FStorm, but that displacement is clean, fast, and barely registers on the VRAM