It's not that -aru has no meaning. It's more precise to say that she's imitating Mandarin speakers from Beijing, China because when they speak, they have this strong -er (兒/儿) sound at the end of their sentences.
@Kevadu that's a good question, is there any reason for a man made object like an android, robot, or Golem, to not turn into a cute girl, or maybe even a Gundam?
For a wonderful world where small boobs are appreciated, there are way too fee pettankos in the cast. Well, none. The smallest non loli character has average ones.