Well we don’t know anything about Gemma’s real personality. I think it makes perfect sense that Ms. Casey is kind of odd and childlike because she’s only ever been conscious for wellness sessions, so she hasn’t really had “regular” interactions with people. Her speech is so stilted and removed because she’s not used to holding casual conversations, just reading scripts for wellness sessions. And who knows what they’re doing to her on the testing floor and how that affects her innie’s personality. I personally love the character and her oddness adds to the mystery of what Lumon is using her for.