I think it was to gain access to the Ersatz elevator. I'm not sure if Esme knew there was a floor above the penthouse or not, but I wouldn't put it past her. She had Geraldine Julienne as her informant.
I would not put too much stock into timelines. There are a lot of errors. I think Jerome and Esme had been married a little longer than we are led to believe.
Faith is being sure about what we hope for, being convinced about things we do not see. Hebrews 11:1 For God so loved the world that he gave his only-begotten Son, that whoever believes in him shall not perish, but have eternal life. John 3:16