I’m not a box set expert but from what I have gathered, no. To get that, you have to split the box set into separate albums (with all the tagging and identifying the goes with it). Then you can also set separate art
There are lots for open feature requests for individual album art but this is the most voted-for I could find
As you said, would also need the ability to name the discs and a better way to view and choose them than the silly little menu. I am sure there are requests for this as well