You might try something like a Refresh Window script step followed by a 1 second pause script before doing whatever you want to indicate loading is done. The pause should not execute until the Refresh is complete, but be aware that I have not used it for testing window refresh steps specifically (though I have used it to assure that other script steps completed).
If these users will be using WAN connections, this could be really slow. If they will be using Web Publishing access, then a refresh probably can't be triggered for the script described above.
How are your "international" clients connecting to your served files?
They are on a WAN. As currently structured it looks like it's taking about 3-5 seconds between the time the selection is made and when the screen draws the new data. They can tolerate the wait if I give good feedback about what's happening. Otherwise, web is probably my best option.