Jamie Hector was excited to explore his character J. Edgar's Haitian background because his mother and aunt are from Haiti. When he told them about it, and they were excited too and gave him feedback about the dialogue.
According to writer-producer Eric Overmyer, at the beginning of every season the writers have asked, "How can we get Mimi Rogers into the show?" So everyone was pleased that she was around basically full time for season 5.
In episode 502, we learn more about J. Edgar's family backstory. His parents emigrated from Haiti, coming to LA when he was two years old, and spoke Creole at home. Jamie Hector, who plays J. Edgar, was also born to Haitian parents who spoke Creole.
For Mimi Rogers (Honey Chandler), transitioning from Bosch's nemesis in previous seasons to defending him in season 5 was a dream come true. She had hoped the tables would turn that way at some point and he'd need her help.
Despite the antagonism between Honey Chandler and Bosch, Mimi Rogers felt it was clear in season 4 that Honey respects Bosch and believes in what he's doing, so when he asks for her help in season 5, it's not just the irony of the situation that appeals to her. Mimi thinks the writers did an intelligent, subtle job of laying out the relationship between Honey and Bosch.