I think Wlad can actually get a more authentic taste (he's a flavor wizard, after all), but I don't think he should do it since the juice is so popular. In my head, I see the "rice-yness" from Rick's Request added to the Boba Tea. That would give it the tapioca-ball flavor that Raina thinks it lacks.
You may be onto something. Maybe that should be profiled for her, after all, changing a juice is a snap for him to the customer. I do get what you are saying, though.