This is one of the drawbacks of the “Approve All” button. While it makes my life easier many times, it only seems to take one major foul up for me to start contemplating a request to have it removed.
One option is to ask the scout to upload a scan of the blue card as a Comment on the individual requirement. At least that way, it allows the leader to verify whether or not it was signed-off, even if it doesn’t solve the “bulk approval” issue. If it’s not signed on an actual blue card, they could upload a copy of the relevant email as an image.
Another approach might be to request that the scouts not mark requirements as “complete”, but rather add a comment that indicates it was completed and reviewed with the counselor, and as of which date. They could track it for their own purposes either on a blue card, or on a print of the blank blue card from Scoutbook.
Are there a lot of MBCs – working with your scouts – who are not using Scoutbook? I’ve been relatively successful getting the MBCs to try out using Scoutbook, even the somewhat more techno-phobic ones. They generally don’t like it as much, nor use it as efficiently, as the physical blue cards. However, they do see advantages over trying to track everything through various emails. Some of the ones who don’t use Scoutbook are signing a physical blue card, then emailing photos of it to the scouts whenever requirements are reviewed/approved over Zoom. That seems like a lot of extra steps to me, but I’m also fairly comfortable with Scoutbook.