The individual % are already counted for the rewards, event if the world quest fail, and the global goal is not reached, you still have mysterious shards as a rewards, that you can exchange for mysterious tickets.
I think a good suggestion for this kind of world quests would be to separate the world quest and the forms hunting, or let the forms hunting after the world quest, cause right now, with 5 differents forms, a lot of people, including myself, were farming the forms, and not catching any bidoof after the 0.5% reached. Forms available only if the global goal is reached could be a great motivation for everyone.