Thank you for the response. I just got this wrong a second time simply because "kind" isn't a term I associate with animals. I understand it's completely a cultural assumption on my part. For whatever reason I keep wanting to put säyseä (docile) instead.
"Onko Mirri hyvätapainen lemmikki?" should be accepted. "Well behaved" does not refer to kindness but behavior, and "hyvätapainen" is the first translation that comes to mind when directly translating "well behaved".