you should add both of these to https://github.com/dimagi/commcare-hq/blob/master/corehq/apps/app_manager/static/app_manager/json/case-reserved-words.json (yes, unfortunately this is a thing). I took the liberty of checking existing apps to see if any were already using these property names (in couch: /commcarehq/_design/hqcase-tmp/_view/all_case_properties?group=true). unfortunately hsph-dev is using `closed_by` in 3 case types. hopefully they are doing exactly what you want to do here in which case they can just remove that logic and/or it will work fine, but will check out the app.