So, apparently it was just a bug that destroying the summoned Wisps at Wisplight Glen WB counted as amorphous foes for the purpose of the daily endeavors, because now you can destroy dozens of them as they rain down upon you while fighting the boss, but not a single one counts.

This seems to be in line with the change to Big Ozur's Valley WB where destroying the summoned molten pillars no longer counts as killing giants as it did before.
I don't think this bodes well for destroying the stone totems which are summoned by Miregaunts.
I've fought mudcrabs more fearsome than me!