There are no such things as curses.
The fact that they won more away games in no way proves or disproves the theory that the blue jerseys are cursed. Most of the NFC East teams have forced the Cowboys to play in their dark jerseys and until recently, the NFC East was one of the toughest divisions.
Using your logic, we should wear the retro uniforms from last year every game from now on as we have a perfect record with them.
We've lost more games in the traditional white jerseys than we have with the retro jerseys so of course, the white jerseys are cursed too!
Oh, and I grew up during the "cursed jersey" years and even then, I'd laugh every time I heard someone blame losses on the "curse".