"when do you graduate from that university?" could this be accepted as well? is there anything in the Indonesian sentence that indicates past tense?
Yes, that is exactly the meaning, because no tenses in Bahasa Indonesia.
I think "When do you graduate [...]" would be "Kapan Anda akan lulus [...]", as "akan" explicitly indicates future tense. Because there is no "akan" here, past tense is implied, as present tense doesn't make any sense.
Just 2 questions back, in the same sentence lulus was passed and wisuda was graduated. Now lulus is also graduated?
Wisuda is like ceremonial for graduation.
Duolingo continues with the translation but a perguruan tinggi is NOT the same as a university! It is lower level. University = universitas.