Why didn't Ultimecia travel back to Hyne`s time? Because if she did, she would have reached a greater impact.

Or did she?
Is there something scary Ultimecia finds about Hyne enough for her not to travel back to his time? Is that why we don't get to view the bizzare image of Hyne because it's way beyond our imaginations?

Would that explain why she used something alternatively; travelling back to the times of Squall and Co instead. When she saw the little Squall back then, she thought that he would be useful; becoming her constant?

Unless there's a limitation to time travel. If Ellone or any entity of the same kind didn't exist back in Hyne's time, there's no way for Ultimecia to travel back to that time. However, seeing as how Ultimecia came from the future, she must have something there to make her time travel become very, very effective. Maybe Ellone's granddaughter?