Translation:He is not a good student, but on the other hand he is very diligent.
Nu, laux mi, laborema studento fakte estas bona studento, ecx li/sxi ne havas tre bonajn rezultojn.
Can one omit pronouns in Esperanto, like in “He is not a good student, but on the other hand is very diligent”?. (This is not an ellipsis but a coordination of verb phrases: “He [is not a good student] but [on the other hand is very diligent]”). Does it work too in Esperanto? Can one say Li ne estas bona studento, sed aliflanke estas tre laborema? It was not accepted by the system though. Otherwise, I found this sentence in the course: Ni sidis sur la bordo de la rivero kaj kaptis fiŝojn, which seems to confirm the possibility of pronoun omission.
alia+flanko = aliflanke. There would be a few different ways to express that in English, one of them would be "on the other hand". It is not a literal translation, it's an expression.