If I may say something on the matter, the main difference, in Spanish, between perfect and imperfect tenses, for what I know, is the status in which the action is, that is, finished (perfect) or unfinished (imperfect). The big issue with the translation of Spanish into English, and vice versa, is that the translation of the tenses is not linear: sometimes the simple past can be translated as pretérito perfecto simple, sometimes as pretérito imperfecto.
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