Aether needs only 5 losses, after that they have 27 cards left, not enough to make a deck, if they slip in one win, then yes, air would need a 6th, unless they converted some cards along the way.
After Jenk wins the first, the rounds would go 2v2 though.
Team Air can afford only 1 loss, with a second loss possible only if they have won 5 matches, and not converted anything 2:1.
So
: 2 Wins, maybe 3 if
gets 5 wins along the way without converting anything.
: 5 Wins, maybe 6 if
gets a win along the way without converting anything.