Hi,
A round check essentially shows that capture was good. So, if a profile can reproduce the 24 patches of the colour checker correctly, compared to the reference data, it indicates that capture was good for it's intended purpose.
You can make a reproduction profile that is accurate, but it would be for specific lighting.
The image below was shot on a P45+, Adobe Standard Profile reproduces the deep blue purple correctly.
With Capture One we got blue instead of deep purple:
Now, you may ask what the real colour is? This shows the colours reconstructed using Patchtool from spectral data:
My Sony A99 gave this representation with Adobe Standard:
But it yielded this one with Capture One:
Now, that is some years ago, 2015. But I still see the same tendencies with C1's profiles.
This is from an old discussion on GetDPI, that also shows the same behavior:
https://www.getdpi.com/forum/medium-format-systems-and-digital-backs/59120-capture-one-lr6-post700029.html#post700029In the later case, it seems that choosing "Studio Flash" for WB gets the purples back, but it turns the leaves yellow. The posting uses white balance on a ColorChecker Passport grey card that is not shown in the image.
To sum up, there are cases where Capture One is not accurate and it is a sensible think to generate your own profiles. But, making good profiles may not be easy.
Best regards
Erik
In general if you can meaningfully improve your total color response using a 24 patch prosumer target in a non rigorous manner (black walls and ceiling, exactly 45 degree controlled size source illumination, long lens, great measure taken to avoid glare, flare, etc), then your starting color profile was pretty crappy.
Making really great color profiles is a lot harder than it seems to most consumers. Most people get overly impressed with their results because they check the profile using the same colors they used to train/create the profile. That's like me telling you my mothers name was Kay, asking you for my mothers name, and concluding that you know a lot about my family when you say "Kay".
If you're doing a lot of of art reproduction I'd suggest looking into a Phase One back, DT Photon Cultural Heritage LED, and Capture One CH. Thats in use at Library of Congress, Smithsonian, Getty, National Archives, etc.