Difficulty level question

Long story short…Played the whole game up to Forerunner, restarted Forerunner to add a skull, picked up at the last rally point. In-game shows Forerunner completed on easy and Waypoint shows it completed on legendary. I obviously have played every second of the game on legendary. Will this effect the ending for me or is that dictated by finishing the final mission on legendary. I just don’t want to play the whole game through and have to go back to Forerunner beat it, then beat the final mission again.