My wife is trying to complete her legendary soup for Taivan achievement, but it is almost impossible because of random and often shard changes. At least three times she had a nice event going with epic quality soup only to suddenly be transfered to a shard with barely any people and poor quality soup.
Blizzard, if you create events that require substantial amount of people to finish them with max results, like this cursed soup, superbloom, etc. then FIX the random shard changes. Its depressing to not be able to get your achievement because of poor or bugged systems.