I wonder if it could be a flash issue. If you look at number 55, which I didn’t take, she has really good detail. Kerry uses an i Phone and may have shot this with ambient light.
I don’t think remote flash is an option, nor are filters for my Canon.
Is there more than 1 type of reference gray? The one I used for photocopying would meter the same as the back of my hand. I use to use my hand in place of the card when I forgot to bring it.
Another trick I use with compact digital cameras is to put tissue in front of the flash to soften it. If you’re using the flash to fill in an already bright picture then that will lessen overexposure problems.
18% reflectance gray is the standard for photography. I have no idea what you would be using in photocopying. I just checked with a spot meter, and my skin is +2/3 stop brighter than 18% gray (as measured against the Neutral 5 patch of a GretagMacBeth/X-Rite Color Chart, equivalent to Kodak 18% gray). My skin is what I would call average Caucasian. There are definitely people with much lighter skin who would have to compensate with a full stop if they were doing a reading off the back of their hand.
If metering off the back of your hand gives you consistent results that you like, by all means, use it.
I used a gray card to set the meter when copying old B&W photos with a film camera. Worked pretty well since my old camera only had a single metering mode. And I must be weird. The back of my hands are always tan, even through the Winter.
Looking back, I think a lot of the interior pictures could be lighter. The Canon manual says the flash is good to 12’ and I’m pretty sure most were in that range. Maybe I need to go to ISO 400. Kerry’s shots look better than mine but I’m not sure if he’s photoshopping anything.