1/ I don't understand the end of the game.
We declare the winner with points or you win if I buy the card #59 ?
Simply buying card 59 does not make you win. You need the most points as usual. Card 59 simply means that in order to win, you ALSO have to have made at least one juice from card 59, in addition to having the most points.
2/ Idiot question (or not) : why 8#59 and not 4#59 and 4#60 ?
So that card 59 (almost certainly) won't run out as you play your last game of the campaign.