No to speech, yes to personality.
... it lacks both the programming and processing power to create its own verbal responses...
When trying to be good at everything one tends to not be particularly good at anything. Mimicoms are very good with speach, information management, and many other assistant and managerial duties but when it comes to combat you never hear of a Mimicom dominating the battle field. Why? Mimic Computers do two things very well, they process data and look like a human. They aren't armored or strong like the Rayleigh, but they weren't meant to be because they are not a combat android.
Likewise, PiCo is purpose built to fill a single purpose, help the pilot kick more ass by handling all the stupid little things he doesn't want to do or physically can't. For FSCorp building a fighter or mecha costs almost nothing, training a pilot takes way more time and resources. If the pilot dies they now have to send severance and care to his family and that is very costly. They didn't build PiCo to be a diplomat so there was simply no point making it chatty. They built PiCo because the fighter I'm preparing to submit is stupid fast and agile and will be the death of unassisted pilots as it's survival is dependent on out running the competition. It's like an A-wing.
Tl;dr PiCo is a robot dog.