- "you cleaned" is simple past which matches passé composé which is present perfect in English
- "you were cleaning" is past imperfect, which matches the French tense
"You would clean the kitchen" is also a valid translation as it describes an action in the past without a defined end point, in this case a past habitual action.
French and English tenses do not match neatly, with most tenses matching two in the other language.
Yes, that's correct, but a valid back-translation is "Tu as nettoyé la cuisine" which is not interchangeable with the original "Tu nettoyais la cuisine". The translations have to work both ways.
"You were cleaning the kitchen" and "You used to clean the kitchen" are the best translations for this.
Eh? Just because one possible back-translation does not match the original sentence obviously doesn't mean it's wrong. That would be ridiculous. By that logic it is wrong to translate Je suis grand as "I am tall" because "I am tall" can be back-translated as Je suis grande.
"You cleaned" is a perfectly valid translation of both Tu as nettoyé and Tu nettoyais.