as I said, i did not try it myself but asked others about it. They claimed it does not complete them and since it’s rather unintuitive from a UI perspective… well^^
As far as I remember it serves as a tool for making newer pilots involved in the process of the rewarding system and make them more familiar with the necessary and so important resources for further advancing in the game. There are many contracts for vouchers that give good rewards and players who don’t have a lot of time completing all of them it is helpful to see which type of game modes they need to play for those to finish directly. Despite of the importance of vouchers many players with rank 7-9 ships don’t even know how they work. Besides, the contracts are auto accepted each time you launch into another battle. The “quick” launch button is for staying in the same player rotation and having faster MMing. It should also complete voucher contracts automatically.