If you object to a question or remark, comment on it. Downvoting it below zero has an adverse effect of making it harder for the language people to find it. I upvoted it back to zero. Please don't downvote below zero.
For the poster: you are probably right, except this course is about Finnish and about understanding Finnish, not about correct English. I do understand why you comment, but if you want to correct these kinds of mistakes, then use the keyboard (every query has a "use keyboard"-button) and use whom. Then when it says it is a typo, say something else is wrong. The reports are guaranteed to be handled by the language people.
I have a question. Wiktionary calls ken (of which ketä is the singular partitive) an old fashioned word that is mostly used in poetic context. Is that true? Or are there exceptions, like the examples we get here in Duo with ketä?