So from what limited information there is along with messing around on level 1, it looks as if this so called "challenge" is really just a way to buy a red star. Is BW that hard up for cash he has resorted to a bunch of micro-transactions? As far as I can tell so far you can play a level as many times as it takes to win, spending conquer credits to repeat at will.
Looking at josko (solely because he's currently the leader on the board) he made it through the ten levels in eighteen games. Anyone who has played with the bots also knows that bots just do what they want and winning against them can some days be more about luck than strategy which would increase the likely number of games someone would need to win in order to beat the level.
Assuming that these challenges follow the standard rules (again, there is next to no information published about them), since josko has finished the challenge first (it took him about three hours after the challenge started to claim first), does that mean this challenge is already over and there is no real point in continuing to play other than perhaps the interest in a blue star? This challenge is supposed to run for a little over two weeks and as of right now, it looks to be won.