Grammar question - wouldn't the accusative indicate that you started to study "last week" (as in, started studying the events that took place during that time frame)? I would expect an adverb in order to express the time frame when the starting happened. "Mi komencis studi Esperanton laste semajne." But then, I'm just coming back to the language from a decades-long lapse.
I'm a native English speaker here.
In fact, "When did you begin to study Esperanto," is correct.
It's just not in the system yet I guess. It would be best to report it if you have not yet done so :)
is not "when did you begin to study Esperanto" a reasonable translation?
2019-07-24; 17:57 U.S. Eastern Time
Mi komencis studi Esperanton en marto 2015, mi pensas. Mi estas la plej malrapida lernanto en la historio de Esperanto, en la tuta multiverso.