I don't feel like a sword fits the character, to be honest.

Hmm. Probably a little more than Metru Nui. Like public transportation mechanicals and automated doors and lifts will be rather common in the core of the city, and there's even an area with multiple generators.
And I misread "On a scale of Mata Nui to Metru Nui" as "On scale with Mata Nui to Metru Nui" which made less sense.
It's Metru Nui +. As comparable to an actual modern city as you can get with Bionicle, without any of the down steps that you'd have to take, and not likely that much telecommunication. Maybe radios though. In some places.
Edit: True, Suva do exist. Mask swapping is possible. But I can't really think of any that fit the one specific character, or any that could grant the effect I want. I should really think more about the personality though.