Is 'when does he come' also possible (it is currently not accepted)?
still not accepted.
According to Duolingo's mail, it is accepted now. (2018/05/22)
In English it's normal to use present tense for this question but In Swahili I would use the future tense. In English we also use future if we want to... "When will he come?" In Swahili "Atakuja lini?"
This got me. But u make sense