The term "perfect flight" is way over-used hereabouts. By definition, it's not possible to attain. And although the pursuit is justified, I believe the end result is over-rated to a point.
I recall one of the top tournament archers of the 80's telling how, after he had won a national title with a couple possibles along the way, shooting the bow/arrow combo through paper and finding the tear proved he was radically out of tune.
The first deer I killed when I got back into trad a number of years back was a complete pass through at 20 yards with a bow/arrow combo that later shooting through paper proved to be also radically out of tune, due to my minimal knowledge of recurve set up at the time.
Now that I got that off my chest... no question tiller can be off, but you can't attain a tune with an arrow in the proper spine range because of it? I'm less sure on that point. I suppose with a production bow, it's possible it got through final inspection so out of whack, but if it was built by a bowyer? Highly unlikely...
At any rate, I think you need to consult the bowyer who made the bow and work from that point of expert advice...