Here is an overview of the test tray:
You can see that the tray has acquired several more fractures, and it is beginning to fall apart, and the pita square has changed from buff to light green. The copper bits didn't melt, but they are all have flaky oxide layers. The elbow is somewhat more flattened.
This photo shows one particularly glossy and melted patch of the tray:
Regardless of the nominal temperature rating for this mortar, it isn't holding up to the temperatures in this setup. You can see some bits of perlite in this shot as well. It appears unaffected.
Finally, the pita square is worth a closer look:
The magenta streak is where there was a piece of copper wire. The cracks look like the result of uneven shrinkage, rather than heat stress
per se or mechanical damage.
The bottom line here is that the refractory mortar I have in hand now probably isn't going to be very useful. I'm reading up on a variety of other options for a hotface and/or cast system components. Here's a link to one particularly extensive and informative thread on this topic: