Update:
I got the van back today (see post 83). It seems like they performed the trans quick learn and drive learn procedure and worked on getting the filling counts on each clutch at or close to 10. I don't know how they did this, but they road tested it several times over several days and and eventually got the clutches from 5, 4, 4, 3 to B14, C9, D24, E11. I don't really know what it means, but I've included the info in case someone else understands and it is helpful.
The van shifted fine this afternoon, but it may be too soon to tell if it has solved the problem. I just hope the fix lasts at least 10,000 miles before I need to have transmission adaptations reset again.