"Who is he?"
A question word can't be the topic of a conversation with は because the topic is contextual information that is already known by those involved in the conversation and a question word like "Who" is important unknown information.
It reads as "On the topic of who; is it him?"
It depends on the target group, but in a most general setting, any words in the common kanji list published by the Japanese government should be turned into kanji. 彼（かれ） and 誰（だれ） are both in the list.
By the way, I believe the contributors need to enter all the combinations of answer in the database. Like this:
There are a lot more possibilities, and it is just not feasible for the voluntary contributors to include them all. So please just move on, optionally report these, and hope that one day we will have more contributors to process these reports.