I was able to find a fairly dependable farm for crackling shards.
the shipbuilders cave at 64, 20 is the place to go.
the mobs are all normal mobs this is not a hyperspawn. but the mobs have a pretty quick respawn times.
I don’t have exact drop rates but i think i got 1 shard every 200-300 kills. most were under 200 but one took nearly 1000. wowhead lists these at 0.7% drop rate, which is only slightly worse than the rares at 1% and you have to wait for those.
redwing falcons at 42, 74 have a better expected drop rate but there aren’t enough of them up at any given time to farm them efficiently.
happy hunting