Complex sentence: This "new" Rogue Squadron destroyed some of the Imperial forces led by Ysanne Isard, contributed heavily to the retaking of Coruscant and fought in the Bacta War, after resigning from the Alliance military, to retake the world of Thyferra from Isard.
Split into simpler sentences: This "new" Rogue Squadron destroyed some of the Imperial forces led by Ysanne Isard, contributed heavily to the retaking of Coruscant. After resigning from the Alliance military, the squadron fought in the Bacta War to retake the world of Thyferra from Isard.