To get one T3 cosmic you need to average 250 currency per round; that means getting Grand Master III (top #100). Looking at the results from the last round, this means having over 100 wins per round. If you don't get up in that area regularly, then forget about getting a T3 and set your eyes on something more reasonable.

To get one T2 cosmic you need to average 125 currency per round (so Champion I) which you can get with around 40 wins per round. The number of wins required to go up a tier after this can be quite high but the extra effort will only be rewarded by getting currency which can only be spent on awakening frags or Awakening / Catalyst souls which aren't exactly rare and you can buy them from the store without the grind.

The amount of effort required to get just one T3 cosmic in this event is way out of proportion compared to dungeons or other events.