the alt for this is incorrect

What should the alt be for this? I want to make sure it is relayed correctly.

perhaps too lengthy for the alt itself - so likely some of this explanation could be used for the <figcaption> itself, and the alt reduced to a bare minimum...

Three diagrams: five square targets with dimensions of 24 by 24 pixels, arranged in a cross (one target at the center, and one target above, one to the right, one below, and one to the left), without gaps - this passes. In the second diagram, the central target is shrunk to 10 by 10 pixels, with a margin of 7 pixels to the other targets - this will fail the Success Criterion. The last diagram shows that to pass, the four outer 24 by 24 pixel targets need to be spaced out further away from the central 10 by 10 pixel target, at a distance of 14 pixels each, making the overall space occupied by the five targets bigger.

alt I have for the first diagram (the one to be added): "A diagram showing target size of 4 targets, side-by-side that are 24 by 24 pixels in size. Another diagram below the first shows these targets spaced apart by 14 pixels on all sides."

The second alt: "A diagram showing three targets, two that pass and one that fails Success Criterion."

I replaced the <figcaption> with;

Three diagrams: five square targets with dimensions of 24 by 24 pixels, arranged in a cross (one target at the center, and one target above, one to the right, one below, and one to the left), without gaps - this passes. In the second diagram, the central target is shrunk to 10 by 10 pixels, with a margin of 7 pixels to the other targets - this will fail the Success Criterion. The last diagram shows that to pass, the four outer 24 by 24 pixel targets need to be spaced out further away from the central 10 by 10 pixel target, at a distance of 14 pixels each, making the overall space occupied by the five targets bigger.

for that first one, i'd suggest tweaking the alt to also include the size in the second case

A diagram showing ... Another diagram below the first shows the same targets, reduced in size to 10 by 10 pixels, spaced apart by 14 pixels on all sides.

or similar

For the second alt text: "Another diagram below the first shows the same targets, reduced in size to 10 by 10 pixels, spaced apart by 14 pixels on all sides showing adjacent button spacing." Or is the last part I added, "showing adjacent button spacing" repetitive you think?

As I said before, I think the point (that you can reduce size but at the same time spacing needs to increase, negating any attempt to compress targets) is much better made by realistic examples that authors encounter / implement in real sites out there - the video controls example, and possibly, an example of rows of dots reflecting slides in a carousel (these being often smaller than 24x24px). The example that is in here now does not map onto anything I have seen in the wild. The only examples I can think of, of targets spread out in two dimensions (rather than aligned along one dimension), are things that would likely be exempt, like place markers on a map. So I'm still not a fan of this example (but if others think it is valuable, so be it, let it be included then).

If there is a discussion about where to proceed from here on this, then I will wait for word then on how and where to proceed.

@detlevhfischer the example is abstract to show how it affects both dimensions. but ... you mention maps. how about north/south/east/west/center type controls on maps...and if an author decides (for whatever reason) to make one smaller? also, there could just as well be further controls top left/top right/bottom left/bottom right, not just limited to this cross arrangement.