It's pretty decent at first approximation (200 DPI version below, with WotC image for comparison):
While it's far from perfect, the quality we've gotten from scans is sometimes so low that this might be an improvement. The biggest issue is that the ink grain is getting lost, which in turn results in lesser detail overall.
If we were going to do more like this, I'd suggest we tweak the actual photography process a little bit. kudit, I see this was taken with an iPhone SE. There are now
a few apps that let you shoot photos in RAW format on that phone, which the default camera app doesn't allow; I suspect that might get us closer. Could you take one picture each of a foil and nonfoil card you own (doesn't need to be the Invention again yet) using one of those apps in RAW format (the resulting images will be something like 30MB each) and send those to me?
EDIT: I'm wrong! Examining some scans of Inventions right next to scans of normal foils from the same scanner, it seems like the Inventions are printed with a
completely different process, such that the rosettes common to normal cards aren't visible at all. It might still be worth trying a RAW image with one of the Inventions, but we're not missing a level of detail the way I thought.
EDIT2: This is what a processed image (before more tweaks to color correction) from a good scan looks like, for comparison: