Since I see no rules defined for the game and since turbo is pretty standard in JRPGs, I gotta ask - are turbo controllers allowed?

It was never being discussed whether or not Turbo controllers were allowed but there is something like a silent agreement that it's not. But it's also not needed since you can advance textboxes frame perfect anyway with a little bit of practise. Just hold down L or A once a textbox pops up and keep holding until the end and it's skipped frame perfect.