The following are the synonyms for COMPLETED for Roget's Thesaurus - and I don't thinks any of the sounds better than completed:
accomplish, achieve, actualize, bring to fruition, bring to maturity, call it a day, cap, carry off, close, conclude, consummate, crown, determine, develop, discharge, do, do thoroughly, effect, effectuate, elaborate, end, equip, execute, fill, finalize, finish, fulfill, furnish, get through, go the limit, go through with, go whole hog, halt, make good, make up, perfect, perform, put to bed, realize, refine, round off, round out, settle, sew up, supplement, terminate, ultimate, wind up, wrap up