"She waited here a long time."
Translation:Ella esperó aquí mucho tiempo.
Not sure if "un tiempo largo" works." It may need to be "por un tiempo" but I know that "espero" without the accent becomes the wrong word (tense and person) "esperó", Missed or wrong accents don't usually nail you but if they change a right word into a wrong word you're cooked." Se/Sé, Si/Sí and several 1st person singular and 3rd person singular preterit verb forms like here.