But Jason wasn't aware of the fact that his excellent eyesight played a huge role in finding the flaws as some of them were only marginal and difficult to spot.
no. just no.
basically Ashura + Indra equals rennegan.
In Kakashi's view, a Sharingan can't complete its Evolution because Spiritual energy of the user is not enough. When the using brother's eye, their Spiritual energy merges so their power increase. It is the reason why its Evolution is completed.