What are the past forms of the verb in “Klarheit schaffen”?

Answer 1

sich Klarheit verschaffen (Ich habe/hatte mir Klarheit verschaffen)

Es wurde Klarheit geschaffen. (Passive)

Since we (Germans) use preferably the "Perfekt" over the "Prätertitum" in normal day to day speech ("Ich habe gegessen" instead "Ich aß" and "Ich bin gefahren" instead "Ich fuhr"), you will rarely encounter anyone saying "Ich verschuf mir Klarheit". It is grammatically correct but you would rather find that in poetic texts and literature.