We raise monarchs too - just the ones we find in our garden milkweed. We released our third this weekend (not much laying happened earlier in the season in our garden). I'm impressed you got them to make J's all close together. Ours seem to want to wander to the ends of the earth first.
We are waiting on a black swallowtail pupae right now.
The last time I tried to raise a swallowtail I ended up with an orange (ichneumonid?) wasp! I've lost a few milkweed cats to parasites or diseases but never when I've raised them from eggs. We used to collect large caterpillars on the Leslie Spit but now it's only eggs from my front lawn milkweed. I also limit the number of eggs I bring in because my setup is pretty small and, as I'm sure you know, large caterpillars require LOTS of food, i.e. many clean healthy milkweed plants! I don't know why the five caterpillars pupated so close together; I guess there is safety in numbers.
I haven't seen any recent reports but based on a couple of recent visits to Rosetta McClain Gardens I don't think this will be a very good year for migrating monarchs, but lets see what September brings.