Two things to try. I say "try" because I've noticed that there is quite a difference between
PCM families and how they react to certain changes.
There are three converter lock/relock delay parameters for the 4-3 downshift. These are listed in seconds. These work well for PMT1 boxes but I know that your tunes are TNAA7 based so the best I can say is to try.
The best solution (but it won't reapply the TC clutch), is to raise the unlock speed in the 3rd gear function to the 4-3 downshift speed. Don't raise it above the apply speed, because it just won't lock then.